Over the door knob design for portable installation 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 and removable key hook prevents jamming Protective weather cover prevents freezing and jamming Molded body and vinyl coated shackle prevent scratching Also available with personalized laser engraving - Learn more Internal Dimensions: 3-1/2in (89mm) H x 2-1/4in (57mm) W x 1in (25mm) D