18650 batteries are the most common type of battery used with in mods and kits. One of the most vital components of any setup, without a battery to power your device it would never function. The term 18650 refers to the size of the battery, with a 18mm diameter and a 65mm height. An 18650 battery has the capability of pushing out huge amounts of power whilst maintaining great battery life. Whilst some vape kits may contain an in-built battery cell, higher powered mod kits  will require at least one lithium battery to power the device and the 18650 lithium battery has been accepted as the industry standard