Pin tumbler cylinder with anti-pick mushroom pins, resists picking. Hardened steel shackle 20 mm - 30 mm, through hardened steel alloy shackle 40 mm and above. Stainless steel shackles (IB) and brass shackles (MB) available which provide maximum corrosion resistance. Numerous KA/MK suites available, provide multiple site security. Double bolted 30 mm and above for more shackle strength. Nano plated steel alloy shackle helps make rusty shackle a thing of the past. Manufacturer: ABUS