Review: Rustu RX-40 Quad XM-L Single 26650 Flashlight from DX

Rustu RX-40

Reviewer's Overall Rating: ★★☆☆☆

Rating As Mod Host: ★★☆☆☆

This light was provided by DealExtreme for review.



26650 or 18650 w/sleeve


Reverse Clicky Tailcap Switch


5 mode: Hi-Med-Lo-Strobe-SOS

(with memory)

LED Type:

XM-L T6 (as claimed)


Tempered Optical Glass


Yes, perfectly





Date Received:

July 19, 2013


  • 26650 / 18650
  • Good mode memory (after 3 seconds off)
  • Good build quality (heavy & thick walled)
  • Very nice anodizing and machining (other than threads)
  • Nice size in the hand
  • Thick glass lens & very hefty aluminum reflector
  • Nice beam pattern with wide spill
  • Tailstands perfectly
  • Springs at both driver & tailcap ends
  • Virtually all 26650’s & 18650’s should fit


  • Emitters not quite all centered
  • Threads were dry upon arrival and squeaky. Rougher than average.
  • O-ring missing where the driver/heatsink finned part attaches to the head
  • High mode under-driven
  • Lack of a medium mode, and low not much lower than high (despite the current draw)
  • Tailcap switch feels cheap

Other Specs/Details:

Lens: 69.8mm x 2.45mm thick

Each reflector: 23.4mm wide x 21.0mm deep

20mm driver diameter, (pill could be opened up to 32mm with retaining ring opened up too)

Pill available depth 29.7mm

(4) 16mm emitter stars

Appearance of sufficient thermal paste used

General Info:

At first appearance this light looks and feels really great! It has great machining and anodizing, has some serious heft to it, and just plain feels good in the hand. But that’s pretty much where the good ends and the bad begins.

The threads arrived dry, are gritty, and squeak badly. I’d say the threads are slightly worse than the average budget light. Each 26650 battery I tried (King Kong INR 4,000mAH raised-top unprotected, King Kong ICR 4200mAH flat-top unprotected, and Trustfire Flame protected) rattled a good bit. Even with the KK raised-top, a severe shaking of the light will cause it to change modes.

Upon disassembly you see that the “heatsinking fins” are really just for looks as the area where the LED’s are mounted in the head do not make direct contact to them. Heat must be transferred from the head through threads to get to these fins. After leaving the light on for about 5 minutes I noticed a lot of heat at the glass lens and the bezel, but almost none at the heatsink fins.

Light Output:

Generally speaking the output on high is quite nice with a very nice wide floody beam pattern. I was impressed with the beam. It still has a very distinct bright hotspot, but yet a bright wide flood. Going through the modes I quickly thought “what the ???” until I realized there is no medium mode but rather a second occurrence of high and then a low that is almost indistinguishable from high. Of course there is the typical strobe and SOS mode following, with the strobe being what I would call medium speed. One surprising feature is that the driver has good working memory which remembers your last mode so long as you leave the light off for three seconds or longer.

I measured tailcap currents with the three different 26650’s mentioned above and noticed that the current increased as I pressed in harder against the driver spring. Seems this light could benefit from a resistance mod at that spring (and even a longer stiffer spring). All three batteries were fully charged a few weeks prior, but were down to a voltage of 4.13v at the time of testing. Results were as follows:

High - 4.06A
Low – 1.12A

High – 4.27A
Low – 1.10A

TF Flame:
High – 3.65A
Low – 1.11A

The LED’s are wired in parallel and the driver is neither a buck or boost driver so the approximate current to each LED with a tailcap current of 4.27A would be 1.07A though that assumes 100% efficiency. A well driven SkyRay King will easily beat this light for output.

Some photos:

Size Comparison against other known lights (left to right:Trustfire TR-3T6, SkyRay King, HD2010, Rustu RX-40)

Broken down:

Emitters (wiring seems to be of good sufficient gauge - 20AWG?):

Thick glass lens and thick o-ring:


Showing the poor threads:

Driver mounting:

Cavernous driver cavity (notice how the head is not directly connected to the heatsinking fins):

Driver removed:

Closeup of driver:

Beamshot on high (184 feet to the shed):

Beamshot on low:

Photo showing the full width of flood from this light (light in the center sitting on the deck rail):

During my beamshot photo shoot I noticed that I can easily light up objects at over 400 feet away. At 750 feet it lights them up very dimly. The light really does have some throw to it too! As you can see above, the amount of flood this light puts out is awesome!


This light is just way overpriced for what it is. Even if you had extra money to burn on a mod host it just doesn’t have the heatsinking to handle much more than the heat it generates now. It’s such as shame since this light looks and feels so nice (for the most part).


Thanks for the review Garry. Light wise how does it compare to the King?

I'd say the King is brighter overall with more flood. The Rustu has more throw.

The tint on the Rustu is a very nice cool white, no hint of purple or green.


Thanks garrybunk for the review.. it actually looks quite good to be honest!

LEDs are in series, not parallel btw. Looking closer they look parallel series ;)

Thanks for the review!

Wow, the cons just don’t seem that bad for only a low 2 star rating (does make sense for mod host). Must be more that isn’t coming through in the pics or review. Yes, it does seem expensive.

@ChibiM: LED's are in parallel, each positive pad is connected, and each negative pad is connected.

@GottaZoom: I gave it two stars due to to cruddy output levels (under-driven on high, no medium - a 2nd high, and a low mode not low enough), poor threads, poor heatsinking, and most of all the high cost. If the cost were more like $25 I'd probably give it 3 stars. I was actually trying to give it 2 1/2 stars, but couldn't find a 1/2 star symbol!

The output on low surprises me. On low it's only giving about 0.25A per LED, yet the output is still quite bright. That doesn't seem right. I did my current measurements with my "good" meter and thick leads too.


Ahh - this is the mystery 26650 light! Nice review! Sure is weird to see higher amps on a KK INR... Wonder what's goin on there, because the driver seems to be sort of direct drive. With the cells rattling, may be perfect for a Moli 26700. It seems to be easily upgradable in amps (Nanjg to 4.9A or so), and for $20-$24 bucks of 4 XM-L2's on copper from IOS.

If the heatsinking were there, yeah, but I don't see it worth putting much money on it.


Might be worth the $5 or so driver upgrade, for me that is. I'd go with 4.55A or 4.9A, then do the usual copper braiding of the springs, and other resistance reducing treatments and see if it would get to 4.5A on the KK's. It's not much of a bump, but with a nice mode set, it would make it more useful.

Actually, if the cells rattle but you got higher amp readings with the spring compressed, then this explains the low brightness because when it's assembled, it's probably running lower amps then what you measured, maybe? A conductive filler piece to extend the spring may make a big difference.

I had not seen this light before, and I had missed JMs review of it too, which had a lot of the same information.

Sounds like 2,5/5 is a decent rating.

But, based on what I have seen from where I am sitting it looks like a great mod host IMO.

Humongous space for driver/drivers, easy to take a part. Backside of the reflector is not flat (easier to get the emitters well focused despite using thick wires). large switch, driver might be easy to resistor mod (if you wanted to live with it that is), good beam, etc...

All the cons you listed are easily fixed in the modding process. To me it also seems that there is nothing wrong with the heatsinking. As far as my experience goes, its perfectly normal that the front of the head gets a lot hotter than the heatsinks on these lights. Unlike a thrower where the emitter is usually close to the heatsinks, all the emitters are quite near the front and far away from the heatsinks. That fact that your lights gets very warm in the head after 5 minutes despite the "low" high current is just a good sign. (I may be wrong though, but it looks good from where I am sitting)

As far as price goes, its not bad, as a mod host. Most XM-L triple emitter lights are usually 30++. Most quad lights are usually 38$++. For a quad XM-L this have a quite large head, which puts it in a more expensive class than the cheapest quad lights..

Ill probably pass though, got an Shadow SL3 incoming. But if I had not bought that (as a mod host) I would have considered this (as a mod host)...

Might even consider it some time in the distant future... ;)

Thanks for the review Garry!


Thanks for the review Gary. I really like that light. I would just toss the driver and make it direct drive with emitters wired in parallel. That is what I did here and it is one of my favorite lights.

Thanks for the review, Garry! I agree with pretty much all you say about this one. I reviewed this a while back and wasn't impressed either. As I recall, I did find it to be extremely comfortable to hold. Other than that...meh.

Nice review Garry!

If you forget stock, what do you think about it as a mod host?

Ehhh…heatsinking isn’t the best and the single 26650 cell format means you can’t go too crazy as a decent quality single battery can only sustain 5 or 6 amps draw so it’s kind of pointless. You could crank it up to 9amps possible but it would only be good for a few minutes and would be hellish on the cell or overheat the light or even both. Consider the high price as a mod host and you are better off modding a King or a Kung. Hope that helps.

What is wrong with the heatsinking compared to similar lights?

Looks way better than the typical convoy with screw in brass pill (I rarely hear about complaints on them). The front of the head where the emitters sits is a one piece aluminium construction, isnt it?

A bit if lapping of the head could be beneficial.. but otherwise it looks good. Or am I missing something??

9-10A is "daily routine" for my Sony 26650 (rated for 50A, they dont even break a sweat at 10A). Could even use King Kong.

With 4 emitters, Vf is less of an issue compared with a 3 emitter light. Is there a reason why a smaller SRK/Kung light should deal better with the heat?

I love my kings, but grip could be more comfortable, and holding around the warmest part of the light isnt always that great in the long run depending on the weather. The rusto seems to take care of both issues, and its got larger reflectors, and a larger head (more surface area to get rid of heat)

Cost could be superlow of you go the budget route. 4x Noctigons + 1x East092 (assuming you get a good one)

Battery life is overrated... 0:)

Flashoholics brings more flashlights instead :bigsmile:

(or just bring a spare battery if you know you are going to need it)

The head doesn't have that much heft to it for heatsinking. I think the aluminum where the emitters are mounted is only a couple mm thick and it's anodized (well that can be removed). The reflector assembly has heft, but it can't transfer the heat anywhere. The threads from head to heatsink are just thin and minimal for contact area to transfer heat. I felt NO heat whatsoever being transferred behind the head after 5 mins (when the bezel & glass were quite hot.


I like the large head but I think it needs a second cell for more current/better run time. Thanks for doing the review!

So I still have this light sitting untouched since the review. What would you do to mod it; give me some ideas. Keep the ideas “budget” though as I don’t want to dump a lot of money into it.

Concerning the driver, can I just short the current sense resistors (or replace them with a really low value) to boost driver output? The R130 & R010 ones, right?