Variable Voltage Battery - recommended for use with Almora Farm or Heavy Hitters vape cartridges. Also compatible with other 510 thread (round) vape cartridges. The indicator light will illuminate red during charging and turn green when a full charge is complete. 510 Thread Auto Starting (no push button). To use the battery, twist off the battery from the charger and twist on your favorite Heavy Hitters 510 thread cartridge. Battery will time out after 5 seconds of vaporization. The battery will flash if the battery level is too low for operation.