I could check the fit in the Convoy S3, S8 and M2. The XinTD X3 is also supposed to be a tight fit for protected cells. I can check my other lights, but I'd have to check them all because I don't know which don't typically fit long 18650 batteries because none of 18650's have protection. That's about two dozen lights so far. I've just started testing my cells using a hobby charger, but I'd hesitate to post my results unless they were similar to what the others were getting, although my first test appeared to jive well with what others were getting in that thread.