The Oxford Boss 16 (formerly known as Big Boss 16 and Boss 46) is a super strong disc lock with a 16mm shackle.The Boss 16 has been independently tested and approved by Sold Secure Powered Cycle (Motorcycle) Gold standard, Classe SRA, SBSC Intygad Produkt, FG and ART 4*.This lock has a key replacement service. When you buy your lock, simply note down the number which comes either attached to the keys on a metal tag or is laser marked on each key.Key Features• Replacement key service is available• Includes 3 keys• Can also be used as a general purpose lock• Hardened steel 16⌀ shackle• High security, independently approved disc lock• Unique double locking mechanism is twice as secure• Attack tested: freeze, bolt cropper, saw, sledge hammer, drill resistant• Anti-jack design• Compatible with a chain (chain not included)