The CGR 18650 is probably the best battery we have used. It is made in Japan and is a safer chemistry battery making it a very ideal choice specially for Mechanical Mod users.
The performance is also great and the lifespan seems to be much longer than most batteries out there. In fact, my very first CGR battery set from two years ago is still usable even after at least 3 mod upgrades with little problems. Your mileage may vary, but this is my experience.
People using older versions of the Provari like to get the nipple top versions for better contact. For lavatubes, I recommend the flat top. People using telescopic mods can get either.
Read our Mechanical Mod Proper Usage Guide first if you plan on using any mechanical mod.