NTK For iPhone 4 4S 4G Ultra Slim External Battery Power Bumper Charger Case Juice Pack In Retail Package with 3 Color Bumper Side Casing: Clear, Black, Yellow iPhone 4 4S External Battery Charger Case Juice Pack Ultra Slim Bumper Case Design with Three Interchangable Colors Yellow, Clear and black 1500 mAh Polymer-Lithum Battery Optimized to charge your iPhone to full power Two Piece Front and Back Cover Design provide Full Protection for Your iphone Custom Cut Out Makes it easy to access all controls of your iphone and cameras