The Master Lock No. 5422D Portable Push Button Lock Box features an 80mm wide metal body for durability. Shackle design offers over-the-door mounting for added convenience. Set your own 4-character combination for keyless convenience and added security. Protective weather cover prevents freezing and clogging; and the molded bumper and vinyl-coated shackle prevent scratches. The Limited Lifetime Warranty provides peace of mind from a brand you can trust.