LifeCHARGE ONT-PWR-34693 2100mAh Rechargeable Extended Battery Case for Samsung Galaxy S4, AT&T, Sprint, Verizon, T-Mobile - Retail Packaging - Black Designed for use with Samsung Galaxy S 4 mobile phones for a custom fit and extended battery life. Carbon-fiber, acrylic and polycarbonate materials offer reliable protection against damage. Built-in 2100 mAh lithium-polymer battery adds up to 8 hours of talk time, 38 hours of audio, 10 hours of video and 10 hours of Wi-Fi internet LED indicators keep you informed of the current charge status. USB connectivity allows you to recharge the case while charging your phone.