The Black Box is a special device designed to fit 510 cartridges of all sizes. The Black Box is equipped with a 900 mAh battery and a battery life indicator to ensure you'll always be ready to go. Included in the package are two different magnetic adapters and two silicone rings to make sure your cartridge fits perfectly with the device. The Black Box features a simple and discreet design, made to fit seamlessly in your hand. The Black Box features a smooth rubberized finish that will make you want to never let go. Specifications: 900 mAh rechargeable lithium ion Battery 37mm(L) X 14.6mm(W) X 69mm(H) Soft Touch Rubberized finish 11.5 mm opening for cartridges