Mjölnir, thy competition has a name: KLARUS XT20 (2 x XM-L U2 | 2 x 18650's)

21 posts / 0 new
Last post
Last seen: 6 hours 43 min ago
Joined: 09/10/2011 - 00:32
Posts: 756
Location: NJ, US
Mjölnir, thy competition has a name: KLARUS XT20 (2 x XM-L U2 | 2 x 18650's)

The mighty war hammer Mjölnir (myol-neer), for those of you who have not caught this summer's blockbuster or are not versed in Marvel Comics' version of Norse mythology, was commissioned by Odin (ruler of the Norse gods) and crafted from Asgardian metal by dwarven blacksmiths using the core of a star as a mold. Although it was a formidable weapon already, Odin further enhanced it with spells that bolstered its powers significantly. Odin eventually passed it on to his son, Thor after he proved himself worthy of wielding it through various trials.

So why might you ask am I mentioning Mjölnir in a flashlight review?

Because it was what came to my mind when I first saw pics of the XT20. Albeit the one I envisioned was not the historical one of yore that bears a passing resemblance to a boat anchor but rather the version popularized by Marvel in Journey into Mystery Issue #83 where Thor and Mjölnir were first introduced. Quite simply, the name translates into "crusher" no doubt due to its intended use. The XT20 could arguably be called as such given the girth in its dual-head which bears two "stars" of its own in the form of XM-L U2's. Let's see how well the XT20 doles out its respective "crushing".

• Two CREE XM-L U2 LEDs, each with a lifespan of up to 50,000 hours.
• Three lighting modes and one flashing mode:
o High brightness: 1200 lumens (2 hr)
o Medium brightness: 370 lumens (5.3 hrs)
o Low brightness: 10 lumens (205 hrs)
• Working voltage: 7.0V - 14.0V
• Battery: 2x 18650/ 4x CR123A
• Body color: Military grey
• Reflector: Textured orange peel reflector
• Entire length: 218.8 mm
• Head dimensions: 68.8mm (length) x 67.3mm (width) x 33.5mm (height)
• Body dimensions: 170mm (length) x 28mm (diameter)
• Net weight: 270g (excluding battery)
• Material: Aerospace-grade aluminum. Hard-anodized anti-abrasive finish
• Waterproof to IPX-8 Standard (underwater to 2 meters)
• Lens: Toughened ultra-clear, durable glass
• Anti-roll and anti-slip body design
• Accessories: Heavy duty holster, removable metal tactical ring, two spare O-rings and spare rubber boot

While the packaging is the typical cardboard w/plastic window and inner shell, I really liked how compact it is. It is not much bigger than the packaging for a single cell light:

Klarus made efficient use of the space available by fitting the head perpendicular to the tube and then using the remaining empty space for the holster and accessories:

Accessories included w/the light:
- Holster
- User manual
- Tactical ring
- 2 large red O-rings
- 1 smaller red O-ring
- 1 black O-ring
- 1 rubber tailcap cover
- Lanyard
- Mini-keychain ring

The Klarus XT20 is not the first light with dual heads as other manufacturers have released various iterations thereof (spotlight, flashlight, bike lights, etc). However, it is to the best of my knowledge, the first handheld flashlight featuring dual XM-L U2's which combine to generate 1200 lumens:

The lens features AR coating (the purplish hue):

The XT20 features dual SS bezels that are perfectly flat, so you won't be able to note if the light is on when placed on its head (I tipped light in right pic so you can see it was on):

My sample came with two smooth reflectors although the manual states textured. There are others who have mentioned receiving one smooth and one textured reflector so best to check with your retailer in case there is a specific setup you'd like:

Just aft of the head are these initial set of cooling fins (there are more around the throat area):

They seem to be reasonably functional and not just for aesthetics. In a test with only an intermittent mild breeze from a nearby windows and ambient temp @ 77.6F, the head was 79F at start. The fins reached 97F after three minutes.

While Mjölnir bears an inscription on the side: "Whosoever holds this hammer, if he be worthy, shall possess the power of Thor.", we are now in the 21st century where laser engravings are commonplace and was employed to carve precisely the manufacturer's name, model and serial number on the flat surface below the cooling fins:

The light respects design symmetries for the most part. The logo on the battery tube is an exception since it's not centered with the head:

Regardless of the position I place the logo when I start threading, it'll always end up on the side opposite the main logo below the fins:

Likewise, aligning the tailcap is the same affair, although in this case, it'll ultimately affect how you can grip the light (more on this later):

Again, symmetrephobes would feel right at home but this will bug those who have perfect symmetry OCD.

The XT20 comes with a tactical ring that is not installed when shipped. It's not the typical screw-on type so I was confounded as to the proper installation given the manual wasn't very clear either. To clarify, the ring can be installed in either direction; flatside towards head (FTH) which is usually the normal way, or reversed with flatside towards tail (FTT):

In either case, the original red battery tube o-ring must first be removed and an additional o-ring installed to fill the gap between the tube and the rim of the tailcap, but the question was which o-ring to use?

Given the red ones seem to be replacements for the originals on the battery tube, I rationalized it had to be the single black one. The problem is if you install it FTH, there is very little room left to install the original red battery tube o-ring:

While installing it FTT allows much easier reinstallation of the red battery tube o-ring, but leaves just a slight gap and also causes it to be free spinning, of which I'd be concerned with the anodizing over the long run:

The rubber tailcap cover protrudes just slightly beyond the tailcap rendering the light non-tailstandable. However, even if it didn't, there is little material to make it stable anyways. I also noticed that it is not perfectly parallel to the edge of the tailcap which might be due to the way it's installed (more later):

The XT20 does not feature squared threads, however the threads are machined precisely and well greased so I had no problems when screwing on the head or tailcap nor did I encounter any grittiness. NEW 9/10: They are also anodized so you can lock it out by unscrewing either end at least 1/4 of a turn. Two AW2600's will sit just flush with the end of the tube while a pair of AW IMR's are a little shorter and sit a bit recessed:

The XT20 features springs in both the head and tail (in which case it's covered by a cap):

Disassembling the tailcap reveals the buttons and electronics (left shot is the side facing the negative side of battery and right is the side facing towards tailcap cover):
NEW 9/10:

Given the two metal prongs that extend out of either end of the tailcap, the cover must be precisely installed to align w/them as well as the underlying buttons:

The switch and its baseplate has a hump that aligns with the groove on the ID of the tailcap:

Here's what it looks like installed without the tailcap cover:

Likewise the rubber cover also has a little hump that is supposed to slot into its own groove within the tailcap:

However I found it was a little tricky getting it perfectly aligned given it is rubber and malleable after all.

Once you have the rubber cover on, when installing the metal baseplate for it, ensure that it slots within the rubber cover and that the rubber extends out all around it, otherwise it may compromise the waterproofness of the light:

When first installing the batteries, I noticed a very brief flash indicating that the light goes into standby (no doubt necessary in order to access instant strobe mode) leading me to speculate that the XT20 will draw some current even when off. EDIT 9/10: I isolated the tailcap and measured a draw of 1.13 µA with a single cell and about 1.25 µA with two (EDIT: Klarus confirmed draw of 4µA but didn't specify how many cells). This is so minute as to be inconsequential, however, if you really wanted to calculate the impact; leaving the self-discharge of the battery out of the equation and taking the highest draw of 4µA (.004 mA) and then dividing it by the typical 2600 mA battery, it'd take 74.2 years to drain the battery in standby (2600/.004 and then divided by 24 and then divided by 365). I don't know about you but I'd be long gone by the time that happens...

Given this is a 2x18650 sized light along with the requisite length and weight, the type of grip you can use and still be able to easily access the switches may be an important purchase decision for some. The XT20 w/tactical ring installed (and no batteries) weighs 8.74oz (247.9g) of which the head alone accounts for 5.16oz (146.4g). Slotting in two AW2600 batteries brings the total weight to 12.03oz (341.1g) just about the weight of your average can of soda (at least here in the states).

The placement of the mode button on the tailcap would necessitate that one hold the light in an overhand grip if they are to be able to change modes. Given the bulk of the weight resides in the head, this leads to a little awkardness and unbalance.

I'll lend this out to people with larger hands to see if they experience the same thing and will report back later as drawing comparisons to Mjölnir would be a little unfair since Thor didn't have any modes to change and thus I bet never had to use the overhand grip.

The holster does an admirable job of holding the light in place. I ran around a bit and didn't feel that the light will come out.

I enlisted two friends to help model the light in the holster. The guy on the left is 5' 7" and the one on the right is 6':

Given the placement of the button on the tailcap, one would need to use both hands to withdraw and turn on the light in an emergency:

When installed, the tactical ring will likely get caught on the bottom rim of the holster which makes it nearly impossible to perform quick, one-handed draws. If easier withdrawl is desired then installing it FTT would make more sense given the taper as it meets the bottom of the holster edges:

The supplied lanyard feels robust enough and should easily support the weight of the light in case you lose your grip.

Based solely on the pics, I had expected the light to be just as big as Mjölnir so imagine my surprise when I finally received it and lo and behold, it's roughly about the size of my M3LT:

From L to R: AW 18650  |  Xeno G10v2  |  Klarus XT20  |  Surefire M3LT

The light is actually relatively compact for a dual-head 2x18650 light.

The anodizing is pretty good but I was able to detect minute areas in the grooves on the tailcap where it seems the anodizing didn't fully "seep in". You may or may not be able to discern this in the pic as you really need to be looking for it to notice it:

The textured finish is not aggresive and only mildly contributes to additional grip, in which case if you're holding the light in an overhand grip with your thumb over the button, it'll be largely irrelevant anyway:

The anodizing is even and matched across the head, tube and tailcap as evidenced in the following pic in which case I compared it to two lights. The top has a mismatched tailcap and the bottom is what I consider to be flawless:

If there is one minor concern to be had, it would be the gap between the tube and the head which really is more attributable to the design rather than any flaw in fit/finish:

I stuck a piece of folded paper in the gap to give you an idea of how much space there is. I estimate the gap to be roughly 4-5 sheets thickness of paper.

As you can see, the gap is large enough for sand and other crud to be caught in there, however, unlike most recent lights I've reviewed, the head is removable from the battery tube so should be easily cleaned in case that happens.

Overall, it's a very solid light but given this is my first exposure to Klarus and I've only had the light for less than a week, I'll report back on how this light holds up in the long term.

The UI is fairly straightforward and is controlled via the dedicated mode button. The main forward clicky only serves to turn the light on and off or be used for momentary on and does not change the modes. There is no memory so the light will always come on in High and then cycle to Medium and then Low in that order.

Strobe can be accessed instantaeneously with the light off by depressing the mode button in which case it will act as a momentary button in short bursts of less than two seconds; if held longer than that, the strobe will stay on. The rate of the strobe will stay constant for as long as you keep the mode button depressed, once you let go, it will cycle between fast and slow. This was not mentioned in the instructions.

To deactivate it, you can either depress the mode button again (to shut the light off) or simply turn on the light via the main clicky. Strobe can also be accessed when the light is on in any mode by holding and depressing the mode button for at least two seconds.

I used various rechargeable battery combo's to provide an idea of what you can expect with similar batteries that you might own. The relevant battery stats are provided above each runtime graph along with:
- Voltage of the battery at the start and end of the test
- Current draw as taken right before the test
- Actual runtime until the battery first starts to cut out (first in HR and then in M so in the case of the RL3100, read this as 2.1 Hrs OR 124 Min)
- For testing on High and Medium (in which case a fan was used), temperature: ambient, the head at start and the max it reached

Axis: X = Time in Min and Y = Relative Output

The XT20 uses PWM on all levels (measurement to come) based on what I'm capturing on my light meter as well as a faint high pitched whine emitted from the tailcap on all modes. However, an interesting thing I picked up after testing all my bat's on H mode was that the light seems to step down roughly 10% in output after 2 minutes and 46 seconds (this is also visible to my eyes).

NEW 10/13: Runtime w/RL3100's added. Due to my revised testing procedures, I stopped the tests when avg. output was below 50% from start. I suspect I probably could've squeezed 20 more min or so before the PCB kicked-in.

Normally I display my graphs in 1 minute intervals (above), which would not have clearly shown this as it looks like the light is just gradually decreasing in output.

This chart below is the same data as above but just unfiltered and is displayed at 1 second intervals to help highlight the very distinct step down which was consistent across all 18650's I used:

Here is the same chart blown up to further highlight this phenomenon:

I have an inquiry to Klarus re: this.

For the Medium test, I forgot to capture the ending voltage for IMR's but suffice to say, one cell in particular was VERY low.

Now here is where I'd like you to pay attention!

I have enjoyed this hobby for nearly four years now and in this time, I have never had a single incident with LiIon cells. I generally take pretty good care of them and charge them in a fireproof container as well as removing them immediately after charge. However, while conducting these run time tests, I am not always around to monitor when the testing finishes. In the event of the IMR's I think one cell got down to around 2.3V. I immediately soft charged it and then stored it away and thought nothing of it. The next morning, I installed that cell along with another IMR and gave it a quick test then put the XT20 on my shelf and left for work. When I got back I turned the light on but it only flashed briefly and then nothing. When I removed the cells to check the voltage, the one cell that was over-discharged was giving all sorts of weird readings. It would start around 2.5v and then start climbing until it was over 4.5V! There was also some weird smell so I quickly dumped it in my fireproof container and then ran out the house with it. I then removed the battery and dumped it into a flower pot full of soil and it's sitting in a corner where it's unlikely to do any damage even if it goes nuclear. I have a feeling the cell vented but given I've never experienced it before, I don't know that for a fact. However, my senses just told me something was very wrong here.

Bottom line is to use sound judgement and to use matched protected cells in multi-cell high-powered lights like this one.

I'm sure there will be the usual pundits who will weigh in and claim their years of experience with unprotected cells and not a single event. But think of it this way, it takes just one event to potentially alter your life forever, why risk it? Don't get me wrong, I'm not trying to drum up the hype machine and become the poster boy for safety advocacy, all I'm saying is use your noggin and play it safe.

Whew, with that said, on with the rest of the review.

The tint is very good with green really only noticeable only on L mode (and even then only when the beam is projected closer to an object). I do notice a purplish halo around the permiter of the beam which I think may be contributed by the AR coating. I'll do some more testing and report back on this.

Before we get to the beam profile, I just wanted to highlight an interesting thing I noted with the LED's and that is that each look to be just slightly-off centered which I believe this was intentional and by design. This is the left head when looking at the light head on, notice how the LED is shifted just slighlty towards the left and there is more of the black gap on the right side:

Now take a look at the right LED and note how it's just the opposite in that the LED is now shifted just slightly towards the right:

I believe this slight adjustment is what allows the beam to point towards the center of the light so that they eventually converge to create a nice giant beam.

Given the compact dual-head set up there isn't room for a deep reflector and as such the beam is more floody in nature but w/decent throw aided by the dual smooth reflectors. I'm confirming with Klarus whether they will eventually offer the other reflectors for sale.

As for the beam, it starts off as two distinct beams that eventually meld into one after two feet or so (sequential shots were taken roughly in 6" increments):

All shots on Canon S3 IS using WB that yields the closest to what my eyes see (left = 1/13" @ f2.7 | right = 1/80" @ f2.7).

Please refer to this post for beamshots and comparo to 17 other lights.

New 12/12: Here are new indoor shots on all modes I took on a Panny FZ150 w/wider angle lens to give you a better idea of the beam profile:



For details of the shots and comparo vs. many other lights, check here.

All shots on Canon S3 IS, ISO 80 @ f2.7 using Daylight WB. Distance to the white wall is 21.3 ft (6.5m) and to the steps (at the forefront of the bottom of the pic is 12ft).

Shutter speeds: left = 1/4" | center = 1/20" | right = 1/80"

Click on pics to load full size.

I recently completed some long distance outdoors shots. For full details and comparo vs. other lights, see here.

As mentioned in the thread, the massively bright floody beam profile gave me the most comfort in this creepy location.

Overall, I really like this light a lot. To echo skyfire's comments "the wtf factor is definitely there" and overall the reaction I've received from friends and family were positive and I got a lot of "Man, that thing is bright!!". However, with that said, while I like this first release, what I'd like to see from the next iteration would be:

- current controlled vs. PWM w/better regulation
- Turbo mode where it's driven at 3A or more for a brief period of time before auto-stepping down
- ability to turn each individual head on/off as this would work really well if you have one smooth and one textured reflector and ability to control level for each head too

Overall a very solid release from Klarus, and again given this is my first experience with their lights, I'll report back in a few months to see how it's holding up.


...goes to my wife for putting up with me and helping take these shots (and the intro one) in which I was trying to emulate that cover from the Thor comic:

This one came close but wasn't as dramatic:

Disclosure:  XT20 provided by eliteLED.com courtesy of Klarus.

Edited by: sb56637 on 08/26/2014 - 17:21
Oxy Moron
Oxy Moron's picture
Last seen: 1 year 7 months ago
Joined: 03/24/2010 - 13:55
Posts: 813
Location: USA

Hey Tim,

welcome to BLF! It's good to have you here. Smile


turboBB wrote:

P.S.  Given this isn't exactly a budget light I was hesitant to post this review so if inappopriate, mods, please delete.

Well, we really don't have mods here. Smile I'm obviously just some guy, but I think you did an awesome job. In fact, your review put the XT20 on my short list when I first read it over at the other place (courtesy of Google; I don't usually go there so I would have missed it if it wasn't for Google). I ended up getting the V60C instead at that point in time because it was such a great deal but the XT20 is still very much in the "DO WANT" category.

Anyway, I just wanted to say thanks and welcome.

sb56637's picture
Last seen: 4 hours 45 min ago
Joined: 01/08/2010 - 09:29
Posts: 5970
Location: The Light

Thanks very much for the review TurboBB, and welcome to BLF! Frontpage'd and Sticky'd.

Budget Light Forum ...where Frugal meets with Flashlight!

Last seen: 1 month 3 weeks ago
Joined: 01/30/2012 - 09:02
Posts: 1780
Location: United Kingdom

quality review!  And an very nice torch, the only problem is the price in the UK.


Thanks, Marc.

Eagles may soar, but weasels don't get sucked into jet engines!

trooplewis's picture
Last seen: 8 months 3 weeks ago
Joined: 03/26/2011 - 15:35
Posts: 2622
Location: San Diego

Nice review, thank you.

That styling of that torch kind of leaves me cold, different strokes I guess. I guess you know you are really a flashaholic when the looks of a flashlight are even a topic to be discussed.

Rats, finally sold my 2010 509hp Mustang...now I can buy more lights!

Sold the red one too! Now guess what I drive, doing my penance for 500 hp commuters...



Aleister's picture
Last seen: 8 hours 14 min ago
Joined: 10/23/2010 - 15:27
Posts: 445
Location: Greece

Welcome to BLF turboBB and thank you for a great review! (waiting impatiently for outdoors beamshots)

It might be BudgetLightForum but we sure enjoy - and some times purchase - more expensive flashlights! Laughing

My flashlight has only 2 modes, day and night...

Last seen: 3 years 8 months ago
Joined: 10/15/2011 - 00:44
Posts: 103
Location: Spore

great review and nice pictures.turboBB. notice both reflectors are smooth.i think the earlier version, the reflector is op on one and smooth on the other. 

Langcjl's picture
Last seen: 1 year 1 week ago
Joined: 03/05/2011 - 05:36
Posts: 2162
Location: Wisconsin USA
Welcome to BLF and great review.

Piers said " ....but who wants enough light, when you have the option for far too much "

BetweenRides's picture
Last seen: 4 years 3 weeks ago
Joined: 01/02/2011 - 10:34
Posts: 2960
Location: Chicagoland, USA

Langcjl wrote:
Welcome to BLF and great review.



jacktheclipper's picture
Last seen: 2 hours 23 min ago
Joined: 10/31/2010 - 21:18
Posts: 4812
Location: Florida , U.S.A.

Your style is eerily similar to a review by our own beloved Flashlight Foy , amusing , detailed , well written , and with fantastic photography .

Thank you very much and welcome to the forum .

Budgeteer's picture
Last seen: 4 years 3 months ago
Joined: 08/24/2010 - 02:19
Posts: 3087
Location: Slovenia (EU)

Excellent review. I don't like the whole flashlight much. But! The head would make a very good looking byclicle lamp for sure. It is however well made judging by the pics.

kragmutt wrote:

They're gonna send you a green redcat with a black LED.

Last seen: 5 years 6 months ago
Joined: 01/28/2012 - 00:40
Posts: 201
Location: Or

Great review.

I feel manufacturers of high power flashlights are missing out by staying with the 18650 batteries (especially in two cell format), if they were to take the plunge and use 26650 batteries the light would be more comfortable to handle it would look more balanced and have the advantage of longer runtime. 

No points for guessing my favorite cells for larger lights. 


People demand freedom of speech to make up for the freedom of thought which they avoid.
Last seen: 6 hours 43 min ago
Joined: 09/10/2011 - 00:32
Posts: 756
Location: NJ, US

Thx for the comments and warm welcome guys!  Please feel free to throw me some constructive criticisms on how I can improve these reviews.  Was there any info missing, are there particulars you'd like to see discussed?

Likewise, if there are any specific feedback about the light (future revisions, specific features) that you have, I'd be happy to pass it back to the mfg (or point them to this link).


@Oxy Moron, albeit a bit old, I'll be porting over the V60C review soon.

@trooplewis - I think styling definitely matters (although subjectively), thus I always dedicate a section to design/features. It's interesting to analyze the thought that was put into the design of each light (or not).

@Aleister - ah yes, the outdoor shots are now up there.  I had posted this a while back but never updated it. I will also be porting over the outdoors XM-L throw thread as well as my Epic Indoor Shots comparo thread.

@MILO - yeah, I think it's best to check w/the dealers if there are specific configuratons one might like. I had requested the OP reflectors from Klarus as I wanted to review them as well but never heard back.  Maybe I'll try again.

@jacktheclipper - I must confess I haven't spent much time here but definitely aim to do so going forward.  Will definitely look up Flashlight Foy's reviews, thanks for letting me know!

@Budgeteer - a gent on the other forum actually did just that and has been very satisfied with it as a bike light.  The ability to add a pressure sensitive switch might make it even more fitting for that use.

@Burro - whoa boy, you're in luck, my next review will be of a 26650+ form factor light ;o)

@gorann - thx!  Photography (especially macros) is another hobby of mine.  Please feel free to peruse my galleries here.


Last seen: 3 years 8 months ago
Joined: 10/28/2010 - 23:33
Posts: 273
Location: Rosario, Argentina


I NEED THIS ONE... my Fenix TK-45 wants a new friend!

"no le temo a la oscuridad, la oscuridad me teme a mí"

Last seen: 1 year 2 months ago
Joined: 02/05/2012 - 02:47
Posts: 64

turboBB wrote:

@gorann - thx!  Photography (especially macros) is another hobby of mine.  Please feel free to peruse my galleries here

You can easily see that! Great review with just beautiful pictures. Thanks for that.


I can't wait for DD to finally ship my XT20. If they ever do so.

Last seen: 2 months 5 hours ago
Joined: 07/30/2011 - 10:13
Posts: 759

Great review. The mjolnir pic is awesome lol.

I like: walks on the beach, sushi and things that are paisley.

fishinfool's picture
Last seen: 1 year 6 months ago
Joined: 03/09/2010 - 00:30
Posts: 4342
Location: Hilo, Hawaii

Awesome review and beautiful pics! 


Don wrote:

"But as I said long ago, you are more likely to be killed by a dead fish dropped by a seagull in the Sahara Desert than by a lithium ion

ChibiM's picture
Last seen: 9 hours 9 min ago
Joined: 05/09/2011 - 10:25
Posts: 5497
Location: Holland/Japan

Thank you for the very detailed review with the superb quality pictures!
Have been watching the light a few times at DD.

Very nice having you around here at BLF... !

Last seen: 2 days 14 hours ago
Joined: 07/13/2011 - 16:18
Posts: 3609
Location: RO

Looks like a hammer indeed.

Inspirational review! Great job!

Foy's picture
Last seen: 2 years 9 months ago
Joined: 01/02/2011 - 17:56
Posts: 3009
Location: Las Vegas

I think it looks awesome.  Too expensive for Foy, unfortunately.



No referral links and nothing embedded . . . ever.


zyobm's picture
Last seen: 5 years 5 months ago
Joined: 03/23/2012 - 00:05
Posts: 11
Location: China

its bulb looks very cool,haha

wholesale flashlight : www.shenzhen-wholesale.com where you can get big discount!