Anker&reg; 5200mAh Extended Battery for Samsung Galaxy S4, GT-I9500, With Dark Blue Back Cover, with NFC/Google Wallet [18-Month Warranty] Made with Grade A Li-ion cells and high quality, durable materials, more than 500 recharge cycles over the life of the battery High capacity: 5200mAh (with an extended back cover) Voltage: 3.8V, Type: Li - ion battery Built-in overload & over-voltage protection, tested under strict quality control standards, certified by CE / RoHS Package includes: 1 x cell phone backup battery, 1 x user's manual