Master Lock 51mm Magnum Laminated Steel Padlock - The Master Lock Magnum No. M5XT Laminated Padlocks feature a 2in (51mm) wide laminated steel body for maximum strength and reliability, and is surrounded by stainless steel and zinc outer components for weather resistance. The 3/8in (10mm) diameter octagonal shackle is 1in (25mm) long and made of Tough-Cut(TM) boron-carbide, 50% 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 can trust. Magnum #1 Choice of Professionals Tough-Cut octagonal boron-carbide shackle is 50% harder than hardened steel Maximum shackle clearance for more uses Dual-Armor(TM) protection: 2in (51mm) laminated steel core for strength surrounded by stainless steel & zinc outer components for weather resistance Dual ball bearing locking for maximum pry resistance Reinforced body bumper for scratch resistance 4-pin cylinder for increased pick resistance Keyed Alike - Same key opens both locks Lifetime Guarantee