This pen battery is designed for oil cartridges or carts. It has a 510 threaded connection, 380mAh battery capacity, preheat function and variable voltage output (2.7V, 3.1V and 3.6V). This pen battery can be recharged using the included micro USB charging cable. How to use: 5 CLICKS the button to turn ON/OFF • 3 CLICKS to adjust voltage: 2.7V (Green), 3.1V (Blue), 3.6V (Red) • 2 CLICKS to preheat (preheat takes about 10 seconds) • 1 CLICK will stop preheat (if you want to stop preheat half way through) Features: • Battery Capacity: 380mAh • Dimensions: 11.2mm wide and 88mm tall • Variable Voltage – 2.7V (Green), 3.1V (Blue), 3.6V (Red) • Preheat