The Criterion chain and mini D-lock has a hardened steel square linked chain (1m x 10mm) for a better cutting resistance. A black nylon cover prevents scratches. The mini D-lock has a unique patented 16mm octagonal shackle for superior resistance against bolt cutters. The shackle is specially treated hardened steel for maximum strength against attacks. The dual locking mechanism gives enhanced pry and pull resistance. A high security disc cylinder with an anti-drill plate for protection against picking and drill assaults. The lock has an anti-dust keyway shutter to protect the mechanism from everyday dust, dirt and grime.