if only this light got stainless steel bezel since i like two tone color in my flashlight
Yeah +1, I do love SS bezels, but they are getting harder to find.
That Rocher AS31 I have on one of those shots is a steal with the big SS bezel. It's got the reflector of a C8 in a little smaller package. Think I paid ~$15 each or so in qty 3.
The thermal protection is probably for the driver. It would be interesting to see what the voltage and current is at the LED? The boost driver is working pretty hard, maybe the reason for the thermal epoxy retaining the driver, I would have thought a heavy / thick retaining ring would be a better sink for it
Thanks Tom E. Nice review. Hows the comparison working shots coming along? 
Yeah, really should measure it - Manker claims 1.3A at the LED, but I'm think'n that's pretty efficient if drawing 5.5A measured at the tail, but dunno how boost drivers typically do.
Edit: Just measured amps at the LED (sorry, not voltage), but I measured 1.08A at the LED (16 AWG patch wire, UT210E clamp meter), and 5.6A 5.52A at the tail with a EFEST IMR 26650 5200 mAh cell. This kind of makes sense to me.
Edit #2: I added this measurement to the OP. The use of the UT210E is a bit tricky. It doesn't seem to stay calibrated - I've had to reset it a couple of times. Also while I'm taking readings, the amps slowly rises, and I'm not sure if it's the driver or the meter doing this, since the calibrated base reading also rises after taking the measurement.
I'm confident the readings are in the ballpark though, less than 0.12A off, if at all.
Nice detailed review Tom E,looks like a winner to me. I wondered if maybe if the U21 has an engineering mode like the U11? Might be worth looking into to boost up turbo or other modes. I am still patiently waiting for Manker to offer a discount (cough,cough).
Nice review, extra thanks for the teardown.
Thanks Tom!
Real nice light, that reflector looks very good made.
(Does it run Narsil ? 
)
I was able to get the driver loose, took pics, hopefully I'll get them up soon. I was able to poke a solder pick tool through the LED wire holes from the top, applying pressure, and broke through the epoxy seal of the driver. It's a two piece driver - one board is the contact board (plus electronics), the other is screwed to the top of the pill, which is the solid shelf the MCPCB sits on. There's a wire harness connecting the two boards, so doesn't seem possible to easily separate the USB charging from the driver electronics.
Good news: the driver can be replaced (stock driver contact board is 21 mm 29.8 mm x 2.05 mm)
Bad news: if you replace the driver, you will lose USB charging, and you would have to glue/epoxy the driver back in place
There's also a 4-5 wire harness coming from the switch, but being there is blue and red LED's on the switch board, that makes sense.
Weird in that the 2nd PCB that holds the USB connector is mounted on the pill top - that has to get pretty hot from the copper MCPCB.
My plan to modding this would be to piggyback in a 17mm FET+1 driver using Narsil, scrap the USB charging, removing the 2nd PCB mounted to the pill top, and going with a dedomed XM-L2 U4 1A, so I can use the existing centering piece. Lumens and throw should be increased, keeping the max draw on the battery about the same or lower.
Do you can say me which diameter the driver has?
It's 21 mm 29.8 mm x 2.05 mm, as mentioned above. Again though, there is another PCB in there.
Thanks for reviewing.
Question: Is there an ugly yellowish inner-circle in the middle of the beam when projected on a light-colored surface?
Wish I had a chance to do beamshots, but I looked at it carefully on a white wall, and I thought the hot spot had a pretty even tint, and nice pure white tone. On Budda's review, those wallshots look green, with a darker tint corona - very different than what mine looked to my eyes.
Right now, I got the light opened up in pieces so can't take wall shots
Thanks Tom! Can you bump the current up, via the resistor (s) ?
Well, actually I tried last night, finding a large R050 on the secondary PCB, and stacking an R120 - light didn't work after that, though the dragon's breath mode still worked. Pretty sure the R050 has something to do with charging, not output. Lots of resistors, but none others that appear to be low value large ones.
Edit:
I backed out the resistor mod, and the main LED no longer works. Not sure if I broke something from the resistor mod, or just from tearing it down - can't find anything obvious wrong. I will probably go ahead and do the full mod upgrade, possibly dedomed XM-L2 U4.
Minor updates in the OP - typo fixes and adding more to reference links. GearBest has a listing page for it now. Could this mean a possible future discount?
Got my U21 today, loaded it up and turned it on and the first thing I noticed, a dot in my hot spot, OFF! Sure enough a spec of crud waiting to smoke up my brand new (milliseconds) old REFLECTOR and Melt down into my emitter! :person_facepalming:
(K70) Disaster avoided, clean and scraped what look like a piece of shiny metal, suspect it came from the threaded reflector, thread shed?
Also noticed that it looks to be a different driver, well the number on the driver is not the same as Tom’s? Mine reads DLO 46
Centering ring, well it’s more of a cup if you will, is sloppy around the emitter,way too sloppy for me. Spot is no where near centered, mcpcb floats and twist’s around, nothing to stop it from rotating on the thermal grease? Found the (-) lead pulled out and all bunched up and the (+) dangerously close, possible shearing action! It will be fixed!
The spot is not well defined until you hit turbo and even then the corona washes it out some from the large (centering cup) that surrounds it? Looks great 1ft from a wall, 10-12ft away not so much! It will be fixed!
This will all be taken care of……I’ll charge her up and see whats up, it will be going against the (Bombeta) Cometa de-domed old XPG2 5.8 amp with the Z1 glass and the stock JAXMAN X1….tonight!
Thanks for the review! Teardown photos/analysis very interesting.
The transition from design to production is a problem in purchasing flashlights from new makers or manufacturers.
Mine does not show the problems you mentioned (I did not examine the driver), but mine might have come from an older production run.
I hope you have contacted Manker.
I got my U21 last week. Same driver as KB. Tail threads well lubed. Other end bone dry zero lube. No crud but same off center led. Centered easily. Good solder connections. Excess thermal paste. No twist noticed when reassemble. Hot spot very well defined at all. Noticed better after TLC. Will also compare with the stock X1. Thanks KB for telling what to look for:THUMBS-UP:
Mine was an engineering prototype, they sent me not realizing til after it went out, so driver probably somewhat different.