The Innokin I.O is an incredibly compact pen-style pod system that is easy to use and operate. The Innokin I.O features a ultra slim design with a smooth stainless steel construction that easily fits in the palm of your hand. The I.O features a refillable pod/cartridge system is automatically activated with a simple draw. No buttons are required to activate the I.O. The I.O features a built-in 310mAh battery that may be charged via the bottom micro USB charging port. The I.O is incredibly versatile and is designed for standard e-Liquid, nicotine salt based e-Liquid, and oil using the included ceramic and kanthal coil cartridges.