I'm confused about these "tanks" on the eRoll? I'm thinking of getting one BUT these "tanks" look like the old cartridges we used to use with the 510s, in the old days when ecigs were just coming out. So are these "tanks" or "cartridges," like a mouthpiece with some filler used to hold liquid?
I know you get 2 batteries with the eRoll, is there a way to charge the spare battery so you can switch it out in case you do use all your charge and you don't want to wait 20 minutes for your dead battery to recharge?