The Master Lock Magnum M175XDLF Heavy Duty Outdoor Combination Lock features a 2in (51mm) wide zinc body for strength and reliability. The 3/8in (10mm) diameter octagonal shackle is 1-1/2in (38mm) long and made of Tough-Cut boron-carbide 50% harder than hardened steel offering maximum resistance to cutting and sawing. The roller pin cylinder provides maximum pick and pry resistance. The hinged dial cover and shackle seal offers superior weather protection and reinforced body bumper protects against scratches. The lock includes set your own combination convenience without the need for a reset tool. The Lifetime Guarantee provides peace of mind from a brand you know and can trust.