Cookies Slim Twist ( 900mAh ) Battery has a variable voltage battery with an output capacity of 3.3V - 4.8V, a 2 click pre-heat mode, and a 510 threaded charger included. The user can change the voltage output with the dial located at the base of the battery. The Cookies Slim Twist has an easy to use 5 click on / off function and maximum power of 900mAh. It is compatible with 510 cartomizers. Features: 900mAh Battery Variable Voltage Voltage Range: 3.3V - 4.8V Preheat Mode 510 Threaded Charger 5 Click On / Off Function