General Spec Function provide much protection for your device Compatibility Apple iPhone 4G Features 3-layer protect – Back cover protectors are protected by another layer of plastic sheet on the top & bottom of the back cover protector to prevent scratching before installation. Anti-scratch – Designed to be protect your back cover from scratches. High transparency – Glass-like finish when applied successfully. Reusable – Designed to be applied and re-applied without loss of “vacuum effect”. No residue – No marks or residue will be left on the surface when removed. Easy Removal – Easily removed by releasing the air vacuum. (Remember that there is only an air vacuum and no adhesive on the screen guard.). Nice fitting – They are cut out to the exact dimension of your back cover and sits perfectly on them.