These scientific PHD Vaporizer Batteries from Pulsar fit most cartridges up to 11mm diameter. A magnetic cart connector with universal 510 threading allows for cartridges to be dropped into the battery's cart chamber, making it simple to switch out tanks. These unique batteries also function as a pre-heat device by pre-warming the entire cartridge for optimal vaping performance. Dual Pre-heat Operation: Cartridge Pre-heat Mode - Heats from the coil up. During the first 1-15 seconds, the cartridge preheats at 1.5v represented with a pulsing BLUE LED. Shell Pre-heat Mode - Heats the entire cartridge simultaneously. During the remaining 15-45 seconds, the shell of the battery preheats at 1.2v represented with a pulsing GREEN LED.