The Master Lock M515 Heavy Duty Outdoor Padlock with Key features a 2-1/8 in. (54 mm.) wide laminated steel body for maximum strength and reliability, and is surrounded by stainless steel and zinc outer components for weather resistance. Key lock includes Rust-Oleum Certified protection which provides a lifetime guarantee against rusting on the lock body, and covered lock body, keyway, and shackle seals offer additional weather protection. Octagonal lock shackle is 3/8 in. (10 mm.) wide in diameter and is 2 in. (51 mm.) long and made of Tough-Cut boron-carbide, 50% harder than hardened steel, offering maximum resistance from cutting and sawing. Lock four-pin cylinder prevents picking and the dual locking ball bearings provide maximum resistance against prying and hammering. Master Lock's Lifetime Guarantee provides peace of mind from a brand you can trust.