I bought this: Hexohm 3.0 Styled 180W VV Box Mod. And, the battery compartment is so tight that I'm afraid I'm going to damage my batteries. All 18650 batteries are not really 18 x 65. There are slight variations. Does anyone know of a slightly shorter 18650 that I can try in this mod. Otherwise, I blew $45 on a brick. Well, I did manage to fit a pair of batteries in to try it out. But, they were so hard to get in and back out that I've never used it since. It feels too dangerous.