The Master Lock Magnum M515XTLH Laminated 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. The Rust-Oleum Certified protection provides a lifetime guarantee against rusting on the lock body; and covered lock body, keyway, and shackle seals offer additional weather protection. The 3/8 in. (10 mm) diameter octagonal shackle is 2 in. (51 mm) long and made of Tough-Cut boron-carbide, 50 percent harder than hardened steel, offering maximum resistance to cutting and sawing. The 4-pin cylinder prevents picking and the dual locking ball bearings provide maximum resistance against prying and hammering. The Lifetime Guarantee provides peace of mind from a brand you know and can trust. Rust-Oleum Certified Protection is a registered trademark of Rust-Oleum Corporation.