High security 3* euro cylinder with key operation on outside and just twist of the thumbturn inside. Protects against Lock Snapping, Lock Bumping, Lock Picking, Lock Drilling, Extraction and more. Thumbturn cylinders provide convenient locking and unlocking without the need to have keys at hand. Great for regulary used doors. Manufactured by Yale, the worlds most trusted brand, our latest security cylinder comes with a unique 10 year guarantee; further proof that this is the lock to choose when securing your home or workplace. Awarded the British Kitemarked TS2007:2014 3 star accreditation by BSI, which is identified on the face of the cylinder as an effective visual deterrent. Also accredited Secured by Design, BS EN 1303:2005 4.9.1, and BS EN 1303:2005 4.9.5. Uses an advanced high security dimple and groove key, which can be used either way round. Each cylinder is supplied with keys, fixing screw, and key code card. Cylinder size is described by combining two measurements. First is the internal size, from the end of the cylinder that would be in the house, to centre of screw hole, and secondly, the external end to centre of screw hole.