Delf’s Contemporary Series Multi Function Locks are for Entry doors that require a locking function for security. Due to their ingenious design, they are able to act as a Highly Secure multi function lock providing the ultimate in convenience in one lock, being able to operate in three ways: Deadbolt Function - Securely lock the door by using the key or turn snib (on single cylinder versions) to throw the latch-bolt into deadbolt mode Locked Mode with Egress Function - Securely lock the door by pressing the inside button to lock it - requiring a key to enter from the outside, but exit by simply turning the lever from the inside Passage Mode - Enables you to open the door from either side simply by turning the lever Double Cylinder Secure sets require a key to lock and unlock on both sides of the door when the lock is in Deadbolt Mode Single Cylinder Secure sets require a key to lock or unlock on the outside of the door, and have a turn snib on the inside for easy locking and easy exit. The Delf Secure range are available to be keyed to other Delf locks and are perfect for replacing old deadbolts or locks where the face hole through the door is bigger than 25mm in diameter but no bigger than 54mm. All Delf Secure Sets come with a 7 year Quality Guarantee Specifications Model name Delf Secure Multifunction Lock Brand Delf Trade Material Zinc Alloy/Steel/Brass Backset 60mm Suits Doors of thickness 33-45mm Product Dimensions Installation Instructions To view and download the installation instructions please click on the links below: Delf Elba Linear Secure