ibattz MOJO VOGUE REMOVABLE BATTERY CASE FOR iPHONE 4/4S (1700mAh X 2) Easy Battery Change - Design allows easy swapping of batteries. Modular Design - Eco-friendly - replace individual batteries instead of changing the entire battery bank. Standard Battery Modules - Uses standard battery modules, using readily available replacement batteries. Well-rounded protection - Offers stress absorbing protection against knocks, drops and vibrations. Fast Charge - Half the charging time compared to a standard 500 mAh usb charger.