I saw them Tom , in your review .
It’s the same way mounted on the UT02 i suppose (some eppoxy) . No retaining ring .
Here's a pic from LJ's:
Ahh, here notice the glue, actually is like white thermal epoxy, not very strong:
That doesn’t give much hope for reprogramming anything.
I have the XPL version.I love the light,a little more lumens and the same throw as my M2Xvn!
Spec 1: XPG2 PDT, Most throw, least heat, tight hot spot $132
ANSI
Lumen: 870
Lux: 320K
Throw: 1130m
Spec 2: XPL PDT, High output, larger hot spot $122
ANSI
Lumen: 1500
Lux: 260K
Throw: 1020m
Ok, so the U21 has/had problems with fried drivers. Is there anything known about the possibility the same problem could occur with the Utorch?
About the fried drivers, really dunno. My died after the tear down for the review, but it was an engineering prototype unit. The other one was used for a few weeks before it died. I haven't heard of any one else having problems, but haven't really heard much at all overall. With all the Manker drama, and the fact it was never offered discounted kept BLF sales down I would think, but it's a great light - really like it's size, performance, quality.
Ahh, ok. Vinh is good at getting the most throw w/focusing. The two I modded using dedomed XPL's do about 1,700 lumens (@30 secs) and 240 kcd, but measured at 5 meters, so could be closer to 250+ kcd measured at 10+ meters.
Thanks for the review. Seems like a good host for modding, stock amps are very low though…
Meh, just got 2 of them today, 2.45amp and 2.22 amp on the other! Purple Efest 4200, Basen and a Imren IMR 26700 all read the same. Dust particles on/in both reflectors and a smear of shmuck on the inside of the lens on one of them! :person_facepalming:
Seem well built, focused. Don’t like the switch, sets too low for my liking, too much travel a PITA to activate for me any way, FAT fingers!!! Just wish they were cleaner inside, I’ll try blasting the crap out and clean the lens. :rage: Hopefully they will clean up? 
“The Manker Drama”. Sounds like a Netflix series.
Isn’t 2.6amps on turbo kind of low? Maybe not. I was expecting more though.
It’s a 12V led…
Yes but amps were taken at the battery where it is still 4v. So led amps is well under 1amp
Ah, ok. I think this was one of the odd things of the U21; the light wasn’t pushed hard at all, nothing like the E14 for example. The light was ok, but nothing more than that…
UT02- 2.6A , U21-5,5A on Turbo
Sorry, it’s messed up in my head lol.
As far as the XHP-35 goes, 2.6A is the sweet spot, output drops off after that. That’s emitter amperage though, I don’t know what tail current should be on this particular light to achieve optimum emitter current.
Edit: This is both in my experience and with testing TA is doing. 
Amps at the cell is like 4X the LED, roughly, maybe little more. Should be doing over 5A because stock, the U21 was like 1300 lumens, so in the 1-1.5A range, think it was spec'd at 1.3A at the LED. Wonder if he had it on true turbo... I've made that mistake before.
Since these boost drivers are a bit more finicky, don't think you can crank them up much, plus it's a huge pull of amps for a single cell - 2.5A at the LED is at least 10A from the cell. Good reason to convert the driver over and go with a conventional single cell LED, like the XPL. I got just over 1,700 lumens on a dedomed XPL in this light.
Thank you for the review so far, the amp draw is very low, I have a X1 with a boost driver it pulls 7,34A on a rested King Kong 4000 mAh ICR26650 at the tail for 1,47A at the LED. I think it should be pulling at least 5A to get 1A at the LED.
I have already contacted Gearbest and i’m waiting for more info about the driver . It should pull 5-5.5 amps .
Intensity is lower too , something isn’t ok with the driver .
Making not look forward to the delivery of mine now. Hmmmmmmm……