Kryptonite New York Noose and Evolution Series 4 Disc Lock 12mm, 6-sided chain links made of 3t manganese steel provide maximum strength Cinch ring design enables effective lock up with less length of chain Durable, protective nylon cover with hook-n-loop fasteners to hold it in place Evolution series 4 Disc Lock features a 14mm hardened MAX-Performance steel shackle with double deadbolt locking for additional protection against twist attacks Patented, hardened oval crossbar design is stronger than a typical round tube