I run mine with Vapcell F38, in an S3 host.
Tried using Molicel p28a to see if it was an issue with my F38, and it had the same results.
I found it strange but it doesn’t bother me too much for now.
That sounds great, when can I buy it? 
I just discovered something cool when scrolling the shop - we can now select 18350 batteries when ordering 18650 lights that have tubes available, and Simon will automatically swap the tube. No more need to order separately. Also, thanks for adding the M11 v2.0, Simon!
This is great news for a 18350 fan like me 
On another topic - @Simon_Mao I saw you listed the SFT-12 now, do you have a datasheet available for it? I am not aware such a thing exists in public yet, maybe you got one as a seller and are allowed to share?
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That is great, very useful for me since I almost only use my S2+s with 18350 tubes.
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I love the S2+ golden.
Hopefully the brass S2+ is available soon.
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I still want a green host with green led, red host with red led and blue host with blue LED, all 18350 
Would fit nicely next to the gray host with B35AM and the purple host with UV.
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I just saw the M21J pop up. It’s intriguing.
I wonder if there will ever be a 2 X 26650 and/or 2 X 26800 version of it (like the L6 and L7.)
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Any advice on the battery choice?
From the product description:“Battery type required: 2*21700 batteries (can bear 10A current)”
Vapcell F60 6000mAh seems like a good choice as they supply plenty of amps (12.5A) an have the highest capacity. Would there be any advantage (brighter light) by choosing Molicell P42A 4200mAh?
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The advantage would be capacity/runtime, if you bought something like the Samsung 50S (5000mAh) or Molicel P45B (4500 mAh) to put in it.
This light uses a 20.5A buck driver rather than a linear driver, so as long as the light is getting 10.25A from each cell, it will be at max brightness. Putting in batteries capable of higher current won’t increase brightness, although depending on the cell, it may shorten runtime due to lower capacity.
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So if I understand correctly the longest runtime would be with Vapcell F60 and other batteries with higher current (50s/P45B) would not change the brightness but only lower the runtime, correct?
Correct.
On the subject of the Vapcell F60s, I can’t comment yet from personal experience, but the F56 (the same thing but the 5600 mAh version instead of 6000 mAh) is VERY tight in some of my flashlights, to the point where it’s difficult to get the battery in and especially back out again.
If the F60 really does hold another 400 mAh, the cell would have to be slightly fatter or longer than the F56, which is already borderline too tight for my taste. I would stick with the Samsung 50S, personally, because I know it fits in everything, it’s a 25A cell, so you won’t have any problems with voltage sag in most lights, and 5000 mAh is still very good for capacity.
The Molicel is great too, but the capacity isn’t quite as good. Great for high-draw lights.
Thank you for the info about the size of the F56 and the advice, I appreciate it!
They pair nicely with the convoy copper piller drivers though. I’ve 2 F60 that are generally inside the m21f and m21h. It doesn’t play inside the tube when swung around and won’t blinks when placed head-up. With molicel p45b I’ve to wrap it to avoid the play inside the tube.
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I’m sure that there is a small variance (even with the same exact model flashlight due to tiny manufacturing differences) in the diameter of all 21700 flashlight tubes. The F56 is alarmingly tight in all of my S21Ds, but it does function fine thus far (other than taking it out to charge, where I have to unscrew the head and tail cap to push it out.)
Do you happen to have a M21G? The M21J looks to use the same tube, so if the F60 fits in it, they’ll likely fit in it as well.
My gut feeling for a light like this, with 2 batteries being in series, is they should be well matched (same internal resistance, voltage, age, model, cycles, charged together, married for life). I would go medium CDR like Samsung 40T / 50S or Moli P45B etc, companies that have good consistency cell to cell. You will not see any advantages of the F60 under these kinds of loads. If 10A is the stated “minimum”, for safety I give myself some margins like 15A+ real CDR … unless you plan on using the light at 10% mostly, but who gets a SBT902 2 X 21700 light for 10% 
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I see the FFL emitters being pretty popular recently. Could you maybe add a few of them to your stocks Simon?
I’d be interested in testing a FFL351A 1800K myself. Seems to be the best 1800K emitter on the market right now. Very niche, obviously, but I would like to own a light with it.
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I kind of doubt Simon would source LEDs from an intermediary flashlight maker (and that FLL would sell them to Convoy, but maybe I’m wrong), ideally Simon would find who is the LED manufacturer of the FLL LEDs and source them directly to the desired specs.
Indeed these LEDs and manufacturer are interesting because the performace of the FFL351A is on par with Nichia, they can do custom color binning and obviously small volume production. It should be no problem for simon to order bulk since Convoy sells much more flashlights than FFL.
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That would ofc be even better. The community couldn’t figure out who’s making those LEDs for FFL, but Simon is in China, is a big flashlight brand and has connections, so he should be able to figure it out and order directly indeed.
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I’m interested too, but I don’t know who produces them (obviously not fireflies)
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