iPhone 4/4S Battery Pack Rechargeable Extended Battery Case by Kiwibird - Black
Ultra Power, Ultra Slim Design  kiwibird is designed for high-usage iPhone users, its 1400 mAh power could give you ultra  power. It has reached ultra-thinness of battery cases! It has slim, light design and is tailor-made for iPhone 4/4S. In addition!!!, Kiwibird is safe and stable, built-in smart chip, equip with anti-overcharge, over discharge and short circuit proof so that could precisely prevent accidents.