Based on the pictures, the S21A is like the S2+, whereas the S21B is like the S11.
Other than that, they seem to have the same UI options and similar emitter options. (The S21B does have some OSRAM variants though.)
The S21A also has an OP reflector while the S21B has a smooth one, but that might be customizable if you placed the order with Simon.
So the difference is just the host shape? They both use the same battery, and I guess either can use any of the choices of emitter and reflector that Simon offers.
Just trying to clarify.
Would be nice if someone could come up with a chart for all the different convoy hosts and what their names mean
Generally, I think Simon meant S, M, and L names to represent small, medium, and large. The numbers in the early days used to be random/sequential according to their design and/or release date. Now, it appears the numbers refer to battery configuration mostly and suffix letters are now the version indicator based on time of design/release. It’s confusing when legacy names / models are still popular (S2+, M2, L6 etc.).
For example, the M21 series are all “medium” sized lights, and use a 21700. The “A” was released first, and there are B and C variants that came after. Unfortunately for those trying to associate the name to a design, they are not in order of size. Small to large goes B to A to C.
Yeah I’ve been able to figure it out mostly based on the photos and random forum posts. In some of the previous models in his Shop he even writes it in the picture/listing (for e.g. M21A - C8+ 21700 version). Would be convenient if that were done on all the relevant models but is probably a lot of work.
I tried with Samsung 50E and 40T - both work fine. Although I’ve put things together by myself but I assume stock version will take 21700 as well. Some “protected” 18650 are 5-7 mm longer so most of producers take it into account. Just pay attention your 21700 is 70mm long, not more. Which means it must be unprotected which (IMHO) is better. But I would recommend to use it with the adapter. S11 can take 26650 which means 21700 may rattle inside. The difference between 26650 and 21700 is 5mm, while between 21700 and 18650 is 3mm. When you bump your flashlight - this may make a difference.
Yes, I noticed this on my M21C-U for 4 mode. This happened on high mode turn off(memory) and turn on again. It also happened for from off, double click to high.
I did some testing. This happened when battery is 3.8 volt and below. With a fresh battery, everything is fine.