Ride Magazine Recommended. Sold Secure Gold. Offers a double use advantage: As a chain lock and as a disc lock. Armoured hardened steel case 3mm diameter protecting the shackle and the locking system. Shackle diameter 12mm. Double locking system with hardened steel balls. 10 disc locking system, with reversible key. Anti-drill / anti-pick. Anti-humidity cover. Hardened steel chain, 11mm diameter. Resistance to traction: 11Tn. For low duty chain locks for bicycles click here: Bicycle Chain Locks