TYLT ENERGI Sliding Power Case for Samsung Galaxy S4 - Blue High capacity 2350mAh battery increases your battery capacity by 90% 2pc design lets you slide off the bulky battery part when you don't need, but the thin inner case allows you to continue to protect your phone Power Case does NOT interfere with your NFC functionality. Compatible with NFC while the case is on the phone Features a multi-color LED so you always know how much juice you have Smooth soft touch finish feels great in your hands. Slim line design provides very minimal bulk