High Security Deadbolt for Entrance doors A key is needed to Lock and Unlock from outside, no need for a key to Lock and Unlock from inside, instead is unlocked with a thumb-turn style lever from the interior 65mm length 22mm Projection off door Modern Design in satin chrome finish 2 x keys as standard Description - A stylish Delf Single Cylinder Deadbolt is a durable, sturdy and secure lock for your doors. Single Cylinder Deadbolts are locked and unlocked with a key from the outside but does not require a key for locking and unlocking from the inside, which instead is unlocked with a thumb-turn style lever from the interior. - A deadbolt lock is distinguished by the locking bolt which extends out of the lock allowing it to go into a wall to secure the door. As this puts a single metal bolt from the door into the wall it makes forcing the door open almost impossible when a deadbolt is locked, perfect for that extra security and protection.SpecificationMaterialStainless SteelFinishSatin Chrome finish Installation - Download Installation Instructions here - What's In The Box