The Veleno Designs 10180 cells are rated 90mAh, and the MecArmy cells are 100mAh rated. I think that’s plenty for a tiny keychain light or neck light. But, I admit that I’d like to see somebody doing development with 14250 size. It’s tiny enough for small lights (smaller than 16340) and also 1/2 the size of AA, so two of them will fit in a 1xAA host (only modders will care about that). But it’s bigger than 10180 enough to get (significantly?) more capacity for even keychain size lights. But those are even more rare than 10180. There are actually plenty of new, modern keychain and/or neck lights still being made with 10180 these days, but they are all made with built in charging so the cell isn’t sold separately.