Kryptonite DoubleDown U-Lock with Chain and Disc Lock The Kryptonite DoubleDown combination bundle pairs a highly secure New York Long Shackle U-lock with a heavy duty New York 1210 chain and New York disc lock. It features top shelf 3T hardened manganese steel construction, double deadbolt protection, keyed-alike convenience and includes 4 keys. New York Long Shackle U-Lock Features: 6mm hardened Max Performance steel shackle Spacious 4 x 10.25 locking area, the largest available at this security level Patented hardened double deadbolt design gives additional protection against twist and cut attacks Highest security disc style cylinder is pick and drill resistant New York 1210 Chain and New York Disc Lock Features: 2mm six-sided, chain links made of 3T Hardened Manganese Steel for maximum strength Extended up to 100cm in circumference Durable, protective nylon cover with hook-n-loop fasteners to hold in place Maximum security New York Disc Lock with 15mm Max Performance steel shackle Patented oval hardened steel crossbar for extra security Hardened Double deadbolt locking for extensive holding power