I would also recommend considering any of CRYSTAL, MARTHA, OLGA, SANDRA, TAMPA and TUIJA.
I have a Crystal, but not so much a fan so far. Will keep trying different emitters…
What did you experience with it? Too many artifacts in the beam?
OLGA-RS has many published beamshots, it seems, that beam shape is nicely scaled by the LED light emitting surface:
https://www.ledil.com/product-card/?product=C16671_OLGA-RS
i will get driver sample soon
Square corona has been the observation that turned me off.
Was the sample L6 sent to maukka meant to be 5000K, or 4000K? As I recall, previous examples of the GT-FC40 seen here had slightly higher than their target CCT, but not by 800K.
Simon, can I ask for my host to be shipped with non-AR coated lens? Only if you have non-AR coated lenses at hand, that is.
In my opinion the usual, current 550nm λ/4 MgF2 anti-reflective coating employed in flashlights lenses sucks. So, in the Name of The Light I just opened a related thread:
About lenses and anti-reflective coatings: a call for stepping up the current technology
Hope you like it. 
I agree with Barkuti!
which flashlight model?
no difference but no coating 
Simon, there’s a competitor flashlight family that I’d like to talk about a bit:
Nightsun HT09-HT12.
What is unique about it is that one can have a single body and multiple lenses.
Furthermore, it actually has easily replaceable pills, giving truly remarkable lego capability.
But it’s not free from failures.
There are some complaints about less than perfect quality. Furthermore, at this size it could easily house 21700 - but doesn’t, it’s 18650 only.
Also, one cannot buy the heads separately, they sell only complete lights. $40 to get another lens? Ouch!
Why do I write about it? Naturally, because you’re in a great position to the same, but do it better.
You already have a 21700 zoomie and from what I heard it’s one of the best out there…and for a good price. And it already has switchable pills.
By offering different lens sizes you could greatly improve its versatility. Have you considered that?
Just to confirm, M21C-U is only available with ramping UI? No 12 groups mode planned?
M21C-U is e-switch light. 12 groups needs mechanical switch. So no.
It can be switched to 4 modes (1–10–40–100). Strobe and battery check are available separately. Pretty good setup. I like it more, than any of 12 groups ones. I have to use it on my M21C-U because of the botched ramping.
Thanks for your answer. I prefer 1-10-35-100 with my 12 modes driver so 1-10-40-100 should be fine for me
M21C has 12 groups
oh ,sorry ,only ar-coated glass lens for S21A currently
S21b with xhp50 available ! It’s output and stability the same like s11 ?
Oh yes, I was really looking forward to the appearance of such a configuration. Now I’m really looking forward to it when it reaches me and I will test it !!
Thanks Simon, the compact flashlight with the XHP50 and 21700 is a very powerful combination. In my opinion the perfect EDC. After installing Dc-fix the diffuser film becomes quite good.
I think that the S21b with XHP70 option will also be interesting.
Or maybe you can make S12 with 3*XHP50? :smiling_imp: