Mammoth Square Motorcycle Chain & Shackle Lock 12 mm The Mammoth square motorcycle chain & shackle lock is a no nonsense heavy duty motorcycle security solution for riders looking to keep their pride and joy secure and safe. The chain and lock is Sold Secure Gold, meaning you can rest assured that your bike is in safe hands while unattended. A protective fabric sleeve ensures that your bike paintwork is safe from scratches. Available in a range of lengths. Motorcycle Chain & Lock Features: Sold Secure Motorcycle Gold approved. Ultra heavy duty lock and chain. 12 x 12 mm Cro-Mo square steel chain. 1.2/1.8 metre chain length. Hardened steel lock body with double bearing lock mechanism. Reinforced cylinder plates resist drilling and picking. 11 mm hardened Cro-Mo steel shackle lock. Protective fabric sleeve. NB - this product was previously available as Thatcham Approved.