This case is a built-in rechargeable li-polymer battery for Samsung Galaxy S IV S4 i9500. Simply dress it on your phone, you'll own 3200mAh external power. Micro input charging port makes it convenient to charge from PC, Notebook, AC / DC adapters just with an extra Micro USB cable (NOT included). Dual IC chips protection, anti overcharging, anti over discharging, anti short circuit. LED Display the electric quantity. Transparent window lets the time, date, power, signal, email, music are viewable. When calls are coming, just sliding the window part to receive or reject them. With a stand, can holding your phone vertically. PAKCAGE: 1 X PHONE COVER