I've had a lot of mods...my edc mod I have now I like so much, I just ordered another...the Tesla XT Mini..
shop around, I paid $70 at a local vape store I was near...found them online for $30-50 (maybe they aren't authentic, haven't gotten the backup yet)
they are just built extra tough and very ergonomic. Designed with a bottom battery cover that's dovetailed in, so if you drop it your batteries done go flying.
RTAs...don't laugh
I've been using eLeaf Lemo tanks for the last 5 years.
I'd be shocked if they are still available, and once my parts dry up for them, I'll have to modernize.