The Joyetech eGo-C Twist 1000mah battery is an eGo style battery with a modified circuit to enable the adjustment of output voltage from 3.2V to 4.8V. To increase the voltage, simply spin the knob at the base of the battery in a clockwise direction. To decrease the voltage, simply spin the knob at the base of the battery in a counter-clockwise direction. The Joyetech eGo-C Twist also has a lock/unlock feature that is activated by pressing the power button 5 times within 2 seconds. The 1000mah battery should last about 10 hours of heavy vaping. The Joyetech eGo-C Twist is incredibly reliable, consistent, and sure to satisfy your vaping needs.