I bought a few M21C-U. As for the reflector rattling, mine all came rattling too and the bezel was not tighten.
I was thinking if Simon let it be loose on purpose so as I can change to OP Reflector that I have bought together.
After tightening the bezel, the rattling gone.
Maybe a fatter O-ring to take up the slack?
There were quite a few “early” lights with both ramping and stepped that I ditched ramping after only a few irritating seconds and snapped it back to stepped-mode only.
And yeah, both Narsim and Andouille do it right as far as ramping. Hell, even my (Airpro) DC7 does ramping right, very Q8ish.
Love your reviews, you are adding something unique that is your own character. 
You are right, what a perfect flashlight, driver, LED, but the UI
Whoever supplied the driver to Simon, did a lousy job.
It could be our fault as well, constantly pushing him for more and more at this price range, maybe all he could do
Thanks for your review Mocarny. I really enjoyed it.
M21C-U seems to be a good flashlight except for its ramping UI clumsiness.
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Simon mentioned that the upcoming Convoy M3-C (M3 with USB-C charging) will have ramping UI, hopefully it (and the next batch M21C-U) will have a better ramping.
Simon also mentioned about M21C-U will be upgraded with USB-C.
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Seems like a good move forward, more Convoy models with e-switch, and USB-C.
Hopefully they’ll also come with a better UI.
Great review and translation.
Great review indeed.
For new M21C -U I prefer non USB-C variant if we want to have best waterproofnes of it. Also most of times I prefer to charge my batteries with external charger. The problem with most powerful flashlights is that USB rubber cover frequently pop out from internal air pressure when flashlight body is hotter. For example SP36.
Yeah, that’s why you gotta love magnetic charging
Just get my black M21C-U with 3000K.
Step changing mode enable after clicking 6 times from off position. And we have 4 comfortable positions: minimal for low light in room (1), second for walking in the night woods (10), third 30, and fourth - 100. Returning to stepless dimming - 6 times clicking in off position.
For me it’t absolutely best mid-range light.
Thanks! I’ll try this on my smaller flashlights. 
Amen.
I hope Simon doesn’t let himself to persuade himself to implement onboard charging into his lights by people who use their lights as toys, where for some people flashlights are tools on which their safety depends on, eg. while caving or doing urban exploration.
How does it compare to M3 in terms of beam profile - throw/spill/etc?
Hi, I updated my review, decreased host and build score because of rattling reflector. I discovered it is not only my problem, my friend ordered about 12 flashlights and each of them has the same problem.
If you have this issue too, let me know.
That’s odd. Mine is tight as hell o_o
Yes, this is a very common but in no way it is a big issue
This is a step by step :heart_eyes:
1- Open your palm.
2-Hold the flashlight by the head
3-Push the head inside your palm
4 Screw clockwise
5 check rattling and repeat 3,4,5 until you hear no rattling,
you can also do it with a self healing pad or mouse pad….
I have 3 M21C-U. All came with reflector rattling. And all 3 the SS Bezel not tighten. Not sure if this is on purpose by Simon as some will prefer to change an OP into this light like I did.
Not a problem for me with them rattling. Once tighten SS Bezel, rattling gone.
By the way, I have more than 10 Convoy lights, all the Bezel came not tighten. Again, I’m not sure if this is on purpose.
I wonder of the tail switch from the standard M21C is compatible and can to be used as a mechanical lockout.
Yes, it can be used this way 
You can even use M21C-U tailcap with M21C and make a non switchable flashlight 
Thanks for the info.
Do you also know if the M21A tailcap fits… and what about the S21A, or S21B tailcap switches?
M21B does not fit, so I assume the rest also will not fit.
Also mine came with reflector rattling. Solved in a minute of course