A sub-ohm battery that fits perfectly M18 tank (diameter of the tank is a few mm thinner). Also suitable for our other products (except EMOW and Aerotank Mini).Automatically adjusts to your tank so that you do not need to set the volts or watts. Very good looking and stylish battery.Delivers up to 4.2V and can be used in tanks with coils down to 0.5 Ohm.Charging via Micro USB cable. Same charger you would see on most mobile phones (not iPhone). Charger not supplied. Can be charged while using battery.Size: Diameter 19mmCharging time: about 2 hours.Life: about 2-4 months depending on the usage.