I use the M2 as well. Although, after having so many issues with my BBB leaking like crazy, I switched to the eVic ProCore Aries tanks, but they can use the same coils as the BBB SO, I think it's safe to say the eVic coils will also work in the BBB. I'm going to be getting some at some point to try them out, I've heard mixed reviews, some think the BBB coils work better, some think the eVic coils work better... I guess we'll see! For some reason the last 2 packs of the M2 coils I've gotten haven't been lasting long at all, like only getting a couple of days out of the coils. I'm not sure why bc the 2 packs of coils I got before these last 2, were lasting well over a week, sometimes 2 (which is amazing bc I use sweet juice)!