The "Integrated Chains" from Kryptonite reduce the attack surface for thieves, as the locking cylinder is directly connected to the link chain and no longer represents a separate part. This further enhances the security of the 9 mm thick, square chain links made of triple-hardened manganese steel. In the combo version, your Kryptolok 990/912 Integrated Chain is secured with a highly durable combination lock featuring a customizable 5-digit code.