The Airistech Vertex 2.0 cartridge battery features a 350mAh internal battery, 3 Variable Voltage Settings, and Pre-Heat Function. To change Voltage level click the power button 3 times quickly and the LED light will change color to indicate the current setting, Green: 3.4V, Blue: 3.7V, Red: 4.2V. To use the Pre-Heat function click the power button 2 times quickly and it will fire at a low voltage for 10 seconds. With a standard 510 connection, this battery is compatible with almost every available cartridge. Brand: Airistech Unit: 1 Set 510 Threaded 350mAh Battery Capacity Micro USB Charging PreHeat Mode 3 Variable Voltage Settings: Press power button 3 times to change level Package: Gift Box Each set contain: 1pc Vertex 2.0 Battery 1pc Micro USB Charging Cable