The Master Lock no. 5422D portable pushbutton lock box features a 3-1/8 in (79 mm) wide metal body for durability. The shackle design offers over the door mounting for convenience. Set your own 4 character combination for keyless convenience and increased security. The protective weather cover prevents freezing and jamming and molded bumper and vinyl-coated shackle prevent scratching. The limited lifetime warranty provides peace of mind from a brand you can trust.