Master Lock Titanium Series reinforced for extreme strength. No rust lifetime guarantee. Bolt Cutter Tough – fully shielded hardened steel shackle offers extreme cut and pry resistance. Weather tough patented sliding keyway cover keeps dirt and grime from jamming the lock. Scratch proof and durable ABS plastic bumper. Key retaining feature ensures padlock is not left unlocked. Shackle dimensions 5/16 inches x 15/16 inches x 3/4 inches.