“REVIEW”: Fireflies ROT66 Generation II – 10000 lumens – 3 x 18650 – 12 x SST20 5000K – Aux Leds – Anduril – [Pic Heavy]


This my review of the Fireflies ROT 66 Generation II.
I won this flashlight in the Fireflies ThanksGiven Giveaway in November 2019.
I thanked Jack and FF more than once, but here’s my public “Thank you!” again!!

The ROT66 Gen II can be found on Fireflies website (non-affiliated): http://www.ff-light.com/index.php?route=product/product&path=59&product_id=50

This flashlight is not necessarily “new” and it had a predecessor, the ROT66. Some information on it here .

Short “notice” comparison between both (taken from the official website):

The V1 was reviewed here:
maukka: Fireflies ROT66 review (3x18650, 9x219B)
Flashaholics: https://www.youtube.com/watch?v=70WVUYC0f7Q&t= / https://www.youtube.com/watch?v=YmlvKTCZ9hs

The Generation II was reviewed on Youtube:
https://www.youtube.com/watch?v=OaHLIiu6iKI& (Flashaholics)
https://www.youtube.com/watch?v=\_L-VyrLTmYQ (d_t_a – Beam comparison)

I didn’t find any review on BLF - please let me know if I missed it somewhere - so here’s my contribution!

NOTE: The specs below are for the model I received. There are other LED options.

Body Colour: Black [other option: Highly-Polished Raw Aluminium (no anodizing)]
Material: Aluminium + Stainless Steel bezel + Stainless Steel tailcap [non included]
Emitters: 12 x SST20 NW L4 5000K (70 CRI)
Lens: AR Coated Glass Lens
Optic: 15º Degree TIR / 45º Bead surface (Pebbled) TIR
Battery: 3 x 18650s
Switch: Side E-Switch
Max runtime: not specified
Max beam distance: 200~700 meters
Max output: 10000 lumens / *
Candela: 40 000 cd / *
Waterproofness: IPX8 (2m underwater)
Impact resistance: not specified [but it fell from ± 1,5m and survived :stuck_out_tongue: ]
Low Voltage Warning: Yes
Reverse Polarity Protection: Probably Yes! [not specified]
Aux Leds: Blue + Ice blue + Fresh Green


  • Digital current regulation on lower brightness

. Values will depend on the leds chosen an, the batteries used and / or the Optic used.
.* Values for the SST20 5000K version.


Before saying anything else about the FireFlies ROT66 Gen II, I must say one thing: this is hand-sized BEAST of a flashlight! This is a small but extremely bright flashlight capable of illuminating a very broad area (way above 200m!!!), what is impressive specially given its “floody” beam!

I must also say that despite not being a lightweight flashlight (due to its robust construction and due to the 3 x 18650s batteries it uses), it feels comfortable to handle it even for someone that doesn’t have big hands. It has a good grip and has good ergonomics (in my opinion).

This said, let’s see what I – happily :smiley: – received from Fireflies.

The box is Fireflies branded, with their logo in the front opening flap (magnetic), the model of the flashlight in the top, a sticker indicating the QC check and the LEDs on the side, and that iconic sentence on back of the box! It couldn’t more correct! From firefly to total day in the night :o

Inside the flashlight is fit inside some thick and protective black foam, along with the accessories.

Along with the ROT66 Gen II, I found: a holster; the User Interface manual; a Stainless Steel tailcap (that I installed meanwhile replacing the original aluminium one, and that is not included in the regular pack); 2 spare white o-rings; a D-ring Tripod Screw with a lanyard; a pebbled TIR optic.


Well, the ROT66 is a small beast (in the good way!), even being a small flashlight! It is well designed, combining round lines in the bezel, body and tail, with a more “octogonal” shape in the head.

It has square knurling pattern on the battery tube, and has cooling fins in the head. Both bezel and tailcaps have no knurling or grooves.

In the “front” (head), above the ROT66 engraving we find the side switch, with rubber cover and bare metal ring around it. On the “back”, diametrically opposed, we find the place for the D-tripod screw. On both sides, we find the remaining engravings, the Fireflies logo on the one side and the flashlight serial number on the other.

The flashlight has 2 main parts: head and body. However, tailcap and bezel can be unscrewed, both to access the head and change the optic or to replace the tailcap.

Going on a short travel from the top to the bottom!
From above we see the impressive and gorgeous 12 Leds under a TIR optic, surrounded buy the stainless steel bezel.

Let’s light it up? :wink:

If we dismantle the “head”, we will see this: the bezel, with an o-ring below it and above the AR Coated Glass lens, and then the TIR Optic. Outside, in the bezel’s threads there is also an o-ring.

This is the “stock” 15º Optic. It has 3 legs and the top of each “led window” is flat, while the surroundings are slightly frosted.

Below the optic…this is the scenario : LOVE:

Aux Leds on Lowest mode.

Aux Leds on Highest mode.

Mains Leds on lowest ramping mode. The Aux leds remain lit up whenever the main Leds are ON, not sure it this is a “default” spec or some functioning “fault”!… Any clue, folks?

With the optic on and a LED detail!

Can’t get tired of this :

Let’s continue downway! On the opposite of the Leds we find the driver. It has a solid brass contact ring where the batteries positive pole will touch. It is held in place with 2 screws.
Below the drivers will be the batteries that will fit into the battery tube (one piece), unlike in the ROT66 V1. On the bottom of the tube there is a PCB with thick springs. This PCB is held in place with 3 screws and is protected by the removable tailcap(s).

The battery tube / body has square knurling outside, and has square threads, both in the top and the bottom. In the extremities it has sealing o-rings. The threads arrived only slightly lubricated.

About the tailcap, here’s a photo with the original aluminium one. I replaced mine almost immediately due to the shiny look and constrast with the black body and the SS bezel :heart_eyes:
Both tailcaps fit well on the tail, but some careful must be paid to the o-ring so that it doesn’t get cut accidentally.

Let’s see how “big” and heavy this flashlight is!
Weight (please note that with the aluminium tailcap it will weigh some grams less)



Now let’s take a look at the accessories.
It cover the flashlight well, but is a tight fit. On the back there “hole” to put it on a belt or attached to some strap or holder (lobster, split rings, …). The opening is made with Velcro.

The o-rings
Well, the ones the the ROT66 Gen II uses are thick, but they will surely wear out so this is a nice thing to have :wink:

Pebbled TIR
Many apologizes, but I didn’t take any photo with it put and the main leds lit up! Just a closeup with the aux LEDs! This is because I see me using more the 15º TIR once it will allow a longer range illumination.
But here it is and how it looks like.

Comparison with the 15º TIR (Right)

D-ring Tripod Screw + Lanyard
Well, this is a big plus of this flashlight! It is my first one with this and I like it! I ordered a big tripod and will soon test it on it :wink:
The included accessory is the screw and the adapter. Attached to it there is a simple black lanyard with a lobster and an adjuster. This is perfect specially because this is a heavy flashlight that needs some secure lanyard to avoid dropping it accidentally.

User Interface Manual
This flashlight uses the Anduril firmware, designed elaborated by Toykeeper. The Fireflies website indicates the source and the mentions the license used. The User Interface Manual is written in English and Chinese (I will only post the English version below).
This is the generic manual for an Anduril User.

NOTE: Please note that although the user manual indicates that there is the possibility to change the aux leds colour, the ROT66 only has the 3 colour aux leds mentioned above: Blue + Ice blue + Fresh Green. Also note that the Aux Leds only have 3 “levels”: OFF, Low, High.

Stainless Steel tailcap
Although I’ve referred it above, there are some things to be said about it. It looks great on this flashlight, it is sturdy, it is well made and it can take a beat! (it felt on the ground from above 1m and didn’t have a scratch :smiley: ) . The only con if compared with the aluminium one, is that it is heavier and adds more weight to the flashlight :stuck_out_tongue:


As said before, the ROT66 Gen II uses Anduril firmware. I will not enter in detail about this user interface.

I will only refer some aspects concerning this flashlight functioning.

Turn OFF or change their brightness (low or high) – The best way to do it is:
>>> from OFF click +4 times to lock* the flashlight (main leds will blink) >>> while locked, click 3 times to alternate between the three states (OFF, Low, High). When you have the state you want, you can unlock the flashlight again (4 clicks).

You can configure the flashlight to have 2 output levels while it is locked, depending on the ramping level configuration you have set! This is a nice feature from this Anduril version.

Apart from these things, the other aspects of this firmware and its functioning have been talked in other threads, videos on Youtube and certainly other forums, so I will not enter in detail.

One mention about the batteries. I am using Sony VTC6 3000mAh high drain unprotected flat top batteries. I am not sure it protected and/or button top batteries will work well so please pay attention, or consult the manufacturer, in case you want to use those cells.


With some flashlights of my collection :wink:

Vs Brinyte T28 Artemis

Vs Convoy S2,Convoy S2,Acebeam H20 and Convoy S2 (18350)

Vs Wuben TO50R and Sofirn C01

Vs Emisar D4 and RovyVon E300s Angel Eyes

Vs Lumintop FW3A (18500) and Lumintop FW1A

Vs Wuben T70 (2 x 26650) and Amutorch AM30 (3 x 18650)

It must be said that I almost didn’t do any comparison with other flashlights!
Why? Because:
a) It was damn freeeeeezing outside during the last days of the year 2019 and I couldn’t held the flashlight and cellphone properly without gloves;
b) Because even with the Emisar D4, the Wuben T70 and the Amutorch AM30, none can be “exactly” compared to the ROT66 !!
c) Because I didn’t feel it was necessary :smiley:

Just a small tint comparison to show how the SST20 5000K leds look like.
And they look slightly “greenish” specially in the lowest modes. On the highest regulated level and on Turbo, they beam looks pure white though!
I never used the pebbled TIR so this may have some influence, as that optic would probably blend the tint a little more.

Tool AA (XP-L HD ~6000K) >>> Emisar D4 (XP-G2 S4 3D ) >>> ROT66 II (SST20 L4 5000K) >>> Wuben TO50R (LH351D 5000K) >>> Convoy T2 (Luxeon V 4000K) >>> Skilhunt M150 (Luxeon V2 5000K)

Emisar D4 (XP-G2 S4 3D ) >>> FW3A (XP-L HI 3D) >>> ROT66 II (SST20 L4 5000K) >>> Wuben TO50R (LH351D 5000K)

FW3A (XP-L HI 3D) >>> ROT66 II (SST20 L4 5000K)

ROT66 II (SST20 L4 5000K) >>> Wuben TO50R (LH351D 5000K)

Wuben T70 >>>> ROT66 II >>>> Amutorch AM30

And now only the ROT 66, on the highest regulated level (left) and on Turbo (right).
Please indulge me because there was some misty fog that somewhat didn’t allow better photos! Still, what I can say is that it lights above 200m and reaches 300m! Eye measured and g8gle map confirmed :stuck_out_tongue:

Overall Appreciation

Despite “you don’t look a gift horse in the mouth”, I will say some things about the Fireflies ROT 66 Generation II flashlight!

This thing is amazing! Really! I may be excited for being my first light with so many emitter and so powerful, but this is really an incredible flashlight!

It is small, it is heavy, it has a good grip, it can fall if you don’t hold it right and open a hole in the ground, it lights the night and it lights the day, it is compact and it is classy, it goes from Firefly to Firestarter in a matter of (mili)seconds.

With all this there are only 2 things that I would like to see in this flashlight: more colours for the aux leds, and less greenish on the SST20 5000K leds.

There is one last thing I’d like to be enligthned about: is it normal that the aux leds are ON while the main leds are ON too? Is it default or fault?

Apart from this, I have nothing else to say! This is a great small light!

Again, thank you Fireflies for this opportunity and for this prize.

Feel free to comment or ask questions! I am sure many things weren’t said…

Nicely done review. Great light that couldn't have been won by a better member .. Congrats !

Very nice, thank you. The V2 has quite different looks compared to the V1 (I like my V1 a bit better) and I would never accept a 5000K greenish emitter again, but other than that this seems like another great light from Fireflies.

Thanks for reading and thanks for your words, mate :wink:
And…I’m sure there are better members out there :smiley: :face_with_monocle:
(although I enjoyed receiving it almost as “birthday” gift” :blush: )

Thanks djozz! :wink:
Well, it surely looks different from the V1! Not having one, I bet this would get my preference, specially because the batteries don’t need a carrier, they’re in the tube, making it smaller and, eventually, stronger (thicker walls).

About the 5000K, well, they are really greenish, I never had SST20s before, despite what I read. I thought they were more towards “yellowish”, but no!
That leaves on option: using it in Turbo :smiley: White wall ahead :smiling_imp:

BTW, taken from Flashaholics video:

I agree that the no-carrier design is better, simple&robust&effective. They did well to change that.

Too much green tint in the sst20
That’s why I bought mine with the xpl-hi for only $ 76.68 at Christmas :wink:
better tint and more lumens
awesome flashlight but missing usb -c

The tint on the TO50R is amazing! I bought two TO50R during the groupbuy and the tint was nowhere near that nice. They both measured a good bit above the BBL. I wonder which tint bin Wuben procured for the more recent batches of TO50R.

How many lumen this light can handle constantly on indoor ambient - room temperature?

Thank you for the great review. Nice fotos and written well! :+1:

Hum, I am not sure and currently I don’t have the possibility to test it! If on the next week I can, I will post here the information!

Thank you for your words and for reading Skylight :wink:


BTW, I wanna add some more photos!
I picked ink spary cap and I started using it as diffuser :stuck_out_tongue:
I took some closer and away pictures with the flashlight in the following modes:

Aux Leds MIN >>> Aux Leds MAX >>> Main Leds LOWEST >>> Main Led HIGHEST REGULATED >>> Main Leds HIGHEST
(Note that the cellphone makes a huge compensation between the 2 highest modes, not showing the real difference seen with bare eyes :zipper_mouth_face: )

Also notice the difference in the white walls between the:
Main Led HIGHEST REGULATED (greenish) >>> Main Leds HIGHEST (white)

You must have spent a lot of time making that post. If you would write text on the images, it would help a lot. But obrigado

Yup, it took me some time to do that, I confess :wink:
What do you mean “write text on the images”? On the comparison beamshots? Any suggestion on how to do that?

The thing is…if I was going to do that, it would take me even more time to make the posts and it would consume me even more time for that…
I try to be as clear as possible when writing and when indicating what the photos refer to! One needs to read and not only look to the images to perceive what they refer to :wink:

I am brand new here in this forum (glad that I found it). You can not paste images here like Facebook (would be nice). You need a image editor. I have used Paint Shop Pro 5 from 1995 !!

First, welcome to BLF and have a good time here!! :wink:

Got it, I know what you mean!
Well, the thing is that it would take me forever to do that and to label all the images on the beamshots.
I normally take dozens of beamshots and photos for my reviews, and choosing them, downloading, uploading, writing the review itself…sometimes it takes me days (not continuously, of course) to have it finalized.

Editing the photos and putting the names on each one would be easier for the readers, but would take me even more sleep time than the one I already spend on these :zipper_mouth_face:

That is why I put the indication above the photos:

When looking for it may be a bit troublesome, but it is the best way i can find to do it currently!

I do appreciate your suggestion and I will try to implement it further! :wink:

Nice review

Thanks buddy

Often it takes time to do quality work. The more U practice, the faster U can do it, but easy for me to say. I am computer wizard.

So far I have spent hours watching YT videos, mostly from the crazy man in Yorkshire, UK, and Advanced Knife Bro

Thanks for your words and for looking mate :wink:

I know what you mean :slight_smile: Besides time, I also have a technical issue… My computer is a bit old and sometimes it crashes, needing forced shutdown, when working with video and/or image, so that is also be another “bug” my system :stuck_out_tongue:
When I get a new one, I will surely try those options :wink:

Both channels are from members from BLF! The first one is “Flashaholics” and the second “mhanlen”!

You have many other members around here that make incredible videos and reviews on YT :wink:
Take a look at these threads and you’ll find some nice suggestions!!

obrigado dear friend in Portugal. I will take a look asap. There are SOOOOOOO many products, reviews, videos etc !!

You’re welcome MichaelDK ! And than you too :wink:

BTW, here’s my new diffuser for this flashlight!
I took it out of a damaged lamp.

Works and fits perfectly :wink:

Awesome Review !

I have this with xpl-hi and it is one of my favorite lights! I didnt know there was aux led trim screws until reading your review just now! thank you!

I found this review in hoops to ask about standby current drain, mine drains a set of new vtc6's in 3-4 weeks. I am going to turn down the aux leds though, that should help bc they are brght! thanks!