Energizer AP1500 Protective Case with Built-In Rechargeable Battery for iPhone 3G/3GS with 1500 mAh - Black Sleek case with integrated battery for iPhone 3G/3GS provides extra power and extra talk time Get up to 4 hours of extra talk time, up to 20 hours of extra music playback, and up to 255 hours of extra standby time Smart battery technology instructs the iPhone to always drain out the iPower2 first Charge and sync your iPhone 3G/3GS to iTunes without removing it from the iPower2 Integrated LED status indicator tells you how much power is left