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 kamk 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