Looking for a spare PRO Series electronic cigarette battery? Keep your electronic cigarette always ready by charging your spare battery when not in use. Available in a short model of 58mm, with the cartridge attached, roughly the same size as a standard cigarette or a long model of 72mm, with the cartridge attached, roughly the same size as a 100's cigarette. The battery component of the eSmoke electronic cigarette is the major component of your electronic cigarette device that contains the lithium ion battery as well as the circuitry and sensor that allows it to operate automatically. Our electronic cigarette batteries are assembled and tested here in the USA and make use of our improved smart-chip to provide the longest usage between charges.