Wall mount design for permanent installation. Protective weather cover prevents freezing and jamming. Molded body and vinyl coated shackle prevent scratching. Internal Dimensions: 89H x 57W x 25Dmm. Convenient push button locking mechanism in familiar alpha / numeric telephone keypad format. Set your own combination using up to 12 letters, numbers, or both. Large buttons for ease of use, even in low light conditions. Large internal cavity prevents jamming, even when holding multiple keys.