Fireflies ROT66

FIREFLIES ROT66 flashlight review:

Table of contents 

  1. Intro
  2. Performance
  3. Conclusion
  4. Fireflies ROT66 for sale
rot66 flashlight black version


What you’ll get:

  • Box
  • Lanyard
  • Spare o-rings
  • Holster

Packaging was done well, and the ROT66 arrived with a very nice storage box. It has a flap with a magnet built-in so it closes nicely! Definitely something to appreciate these days with all the flimsy packaging out there. Even brand names have less nice packaging! So this is definitely a good start for such a new flashlight manufacturer! And includes all the necessary accessories!

Brand/modelFireflies ROT 66
LED9*Nichia 219B XPL-HI
Battery config.3*18650
ModesMany runs, NarsilM v1.2

Handling of the light

Fireflies have done a really nice job on this mini soda can light. If you take a look at the picture below, you can imagine the actual size. It’s pretty tiny but really bright. It is definitely a little hand burner..hahaha. It’s quite compact so you could easily drop it in one of your pockets. The square-sized head and is, therefore, a good anti-roll feature. The included holster is a regular quality holster and isn’t anything special. At the same time can’t say much negative about it either.

The electronic side switch is more responsive than 99% of other side switches I’ve used in the past. In comparison to the BLF Q8 the button is very very quiet and is very sensitive.


  • Yes….and very stable.

Build Quality and Anodizing 

The first thing I noticed (besides the shape of the head) was the shiny tailcap. It’s so thin and light, you can even imagine the weight by just looking at it. That is actually my only negative remark about the quality. It must be some sort of aluminum and not stainless steel. For the rest, it is really up to the standards of any other good quality flashlight manufacturer, but not as high as Acebeam or Jetbeam for example. The mini screw-in attachment hole (for the lanyard) on the opposite side of the switch had some very sharp edges, that could actually cut my finger.


Although the threads are a little on the tiny side, they do what they have to do. All threads came lubed as you can see in the pictures below.

LED, Lens Bezel and Reflector

The bezel is made of Stainless steel, and the TIR optics fit the Nicha LEDs very well. I’ve read some problems with the TIR optics damaging XPL LEDs. So better double-check if you have this problem as well. Update: the XPL version of this light has been replaced with the SST20 LEDs and XPG2. The Nicha LEDs have no problem with the TIR optics as far as my sample goes.

The LEDs used are Japanese Nichia 219B-V1 R9080 who are supposed to be the king of tints.. according to Tint snobs ;–)

They are High CRI emitters, meaning Color Rendering Index. It will produce colors faithfully in comparison with an ideal or natural light source. You can probably remember the first LED you might have bought having ugly blue tints.. That is the opposite of these LEDs. They are high-quality Japanese LEDs.

Of course, it doesn’t use any But it does however use an extra glass lens in front of the TIR optics! I’m not 100% sure why, but I imagine it is much easier and cheaper to replace a glass lens than a 9-LED TIR optic. The lens also has some kind of coating as can be seen in the following pictures.

Dimensions and weight:

Rather compact in size, but still very powerful!

  • Diameter outside bezel: 49.3 mm
  • Diameter widest part of the head: 54 mm
  • ROT66 Body diameter: 44.5 mm
  • ROT66 Length: 110 mm
  • Weight empty: 240 grams

Battery carrier

The battery carrier is fine for what it does, but it looks a little on the cheap side compared to mainstream manufacturers like Lumintop and Acebeam. The springs are double, so they will be able to flow the current through without a problem.

The same as the spring on the driver side. It also has a double spring.

It does NOT accept protected batteries. They will be too long and won’t fit. Only unprotected cells will fit. See the pictures below.

User Interface:

Firmware is (NarsilM Version 1.2)

Ramping (default setting, like the BLF Q8):

From OFF:

  • Single click for ON
  • Click + long press =starts from moon and ramps up

From ON:

  • Single click for Off
  • Long press = ramps up or ramps down
  • 2x clicks =full max brightness level
  • 3x clicks = battery check
  • 4x clicks= lock out on/off  (4x short blinks)
  • 5x clicks= momentary setting

How to reset to factory settings:  

Do the following clicks from either OFF or ON:

3x , 2x , 2x, press&hold (for 1.2sec) till 4 blinks.. HAHAHA.. you bet that was easy right!?

If you use ramping UI only, do not hold the button for over 8 sec, it will enter programming mode. If you are in it by mistake, do not click the switch, but keep pressing the button, to get out of the setting. Better to write that here, than to get completely lost.

Mode memory:

  • Yes. When you press and hold the button to ramp up the output, you can release the button to memorize this setting. Turning off the light with a single click, and enable the light again with a single click will bring it back to last memorized output.

Lock out:

  • 4 clicks will put the light into Lock-out mode. Another 4 clicks to re-enable the light again.


  • Not that I could notice.


In comparison with the BLF Q8, it is definitely within the same league, and doesn’t really enter the list of worlds brightest flashlights, but it’s still very very powerful in such format! Quality wise it is a little above the BLF Q8. Performance wise it is in the same ballpark, but with a totally different LED tint.

I tried to measure the Amps, but couldnt get it passed 1.5A which I know is wrong. So I tried to unscrew the washer on the driver side, but it didnt move. So its probably glued in.

Then I took the bezel and optics off, and unsoldered the + wire and measure Amps at the LEDs. This is actually a much more accurate measurement than tailcap measurement, but it involves more time and effort …

Max output in ramping mode: 5.3 A

Turbo output (double click): 9.01 A.


It definitely is more of a flooder. The hotspot is very very wide. See the shots below. There isn’t much throw to it, so I havent measured that.

Beamshots comparison between ROT66, the Thorfire BLF Q8, Lumintop ODF30 and BLF GT Mini. The ROT66 and BLF Q8 are claimed to have about the same amount of Lumens. The Lumintop ODF has 3000 lumens on paper. The GT mini is just thrown in to show the difference between a “thrower” and a flooder.

Disclaimer: The flashlight was provided for review by Neal’s gadgets.

Overall conclusion of the Fireflies ROT66


  1. Very compact
  2. Nice Tint for the real tint snobs
  3. Very powerful


  1. A little on the expensive side
  2. Tailcap and construction of the battery carrier look a little cheap.
  3. Again the programmable setting can be a little too difficult without manual, but if you don’t touch the settings and only use ramping up and down, you should be fine.

4 stars

It’s one of a kind at this moment with 9 pieces of the Nichia LED which many flashoholics like because of its high CRI and tint. I give it 4 stars because it heats up like crazy, and doesn’t have enough volume to handle the heat very well. 

Fireflies ROT66 coupon:

The Fireflies ROT66 has been replaced by the Fireflies ROT66 gen 2, which in meantime is also discontinued. I would recommend checking out the brightest flashlight list as well.