It's a very common mistake to forget to charge your new iPhone on the way out. The Griffin Reserve Battery Pack for the iPhone 4 can easily charge your iPhone on the go with 30-pin Apple data cable (not included). Provide yourself with extra needed talk and stand-by time. The retractable USB port can be plugged into most universal USB ports for charging. Plug this charger into your computer's USB port to refill the battery level. Then when you're on the go and you need quick fix, connect the type B USB to your iPhone's 30-pin port. 4 LED lights are provided on the bottom of the charger to show you how much battery is left on the portable charger. Carry it in your pocket for easy portability.