The British Standard (BS 3621: 2007) High Security Nightlatch is a high security door lock with a classic and robust design. Operation is by key from the outside and by handle from the inside. An ideal product to replace most existing front door locks and is ideally suited for panelled doors. Particularly for glass panelled doors, as the ergonomic internal locking handle, which can be deadlocked by an anti-clockwise turn of the key from the inside, offers additional security against forced entry. The main bolt is automatically deadlocked into the striker, when the door is closed, preventing it from being retracted by a credit card. Cleverly designed with a 20mm bolt throw for even greater security and strength. A simple snib button on the internal handle, enables the latch to be held in the withdrawn position (only), allowing the door to be accessible without operating the handle. With a face fitted design, the lock is non handed, suitable for both left and right handed doors. The striker (secured to the door frame) has three hole fixings for additional strength and security. The door lock conforms to British Standard 3621:2007 (BS EN 12209) and meets the tough criteria/requirements laid down by insurance companies and the police initiative Secured By Design. Suitable for inward opening external and internal timber doors (not suitable for outward opening doors), the British Standard Nightlatch is available in a range of finishes with matching external security cylinders. The external cylinder features a high security integral cylinder pull, which protects the cylinder from being drilled. With over 30,000 cut key variations, all finishes meet the requirements of BS EN 1670:2007 Grade 3 to provide the most robust finish and security for your hardware.Available in both a 40mm and 60mm backset (backset is the measurement from the edge of the door to the centre of the keyway). Supplied with three cut keys and all fixings/ screws are included. 10 year mechanical guarantee.