JustCase Metallica Ring iPhone 4 4S Aluminum Bumper (Black) - Retail Packaging with Two Free Screen Protector for $29.99

Metallic bumper made by aircraft quality aluminum. Shock-absorbent inner lining made of poly carbonate to further protect your iPhone. The ploy carbonate lining also serves as a non-conductive barrier to maintain the signal strength of the antenna. Easy install. No screws needed. Just snap it on. Lightweight, but strong and durable.