Rechargeable Battery,Mixca 4x18650 LCD USB Mobile Power Bank Battery Charger Holder for iPhone, iPad & Samsung Galaxy & More (Black) Material: plastic and metal. Maximum Supported Battery Length 70 mm Provides extra backup power to all devices that supports USB charging for iPhone6, Android, tablets, MP3 players, GPS units, etc This unit takes 1-4 replaceable UNPROTECTED 18650 li-ion batteries to power and recharge your USB devices 4-slot battery charger case, you can put 1-4 18650, DIR battery capacity Intuitive display, you can always know the battery change