Self-packaged, hardened special steel gives no weak point against sawing, cutting or impact attacks, X2-Power - The "Double Bolt Locking System" features a double bolt lock and increases pull-out resistance by locking the bolt from both sides, BumpBlock M-Cylinder - the steel-encapsulated precision lock cylinder is optimally protected against drilling, tearing out and impact attempts, robust nylon casing protects the frame from scratches, with 4 keys + 1 LED key Art Article Version Chain lock Diameter 6.0 mm Main color black Length 75.0 cm Locking method Key Security maximum