To keep things simple, we'll break down the kinds of e-cigs into two types: disposable and rechargeable. Brands like NJoy, Blu, Greensmoke, and others, make disposable and rechargeable e-cigs: the ones you've seen at the gas station or your local convenience store. Other type of e-cigs are custom vaporizers. These vaporizers allow users to interchange the juice tanks, batteries, and adjust the voltage. They're gaining popularity because they last longer, give a better taste, and are reusable. Custom e-cigs are sold at smoke shops, and new spots sprouting up all over called "vaporiums."