Yale P-2-CH-CH-40 Double Locking Nightlatch, 40 mm Backset, Chrome Finish, High Security, can be Locked from Inside with Key About this item Automatic deadlock is engaged when you close the door for instant security and latch bolt can be held back temporarily with snib button Includes Yale rim cylinder operated by key from the outside with standard security components Internal nightlatch handle can be locked from the inside with a key, ideal for use with wooden doors with large glazed panels Anti-card slip protection, prevents your lock from being vulnerable to this specialist technique that only requires a credit card sized piece of plastic.