Oxford Magnum Duo U-Lock (315mm X 170mm) with Bracket & CableThe Magnum is an ultra strong U lock. It boasts a high security, independently approved 16mm shackle lock with a hardened steel construction and has undergone rigorous testing, achieving Sold Secure GOLD, ART 4*, SBSC and FG certification. The Magnum has a key replacement service. When you buy your Magnum, simply note down the number which comes attached to the keys on a metal tag. Keep this in a safe place, then in the event that you are unfortunate