18650 Mods sold by Evolution Vapes are battery mods that require external battery/batteries. The '18650' Refers to the size of battery. At Evolution Vapes we also sell the external batteries themselves, aswell as the portable chargers needed to recharge them. 18650 Mods most often offer more battery capacity than intergrated internal battery options we have. At Evolution Vapes we stock both single and dual battery mods, Giving you the option of what you prefer. A More bulky Dual mod with more battery life, or a single slot more sleek mod with still very respectable battery life.