Yale Locks P1 Double Security Nightlatch 60mm Backset Chrome Finish VisiYale's High Security P1 Double Nightlatches are suitable for timber external doors and are ideal for glass panelled doors. The lock is key operated from the outside and both key and lever handle operation from the inside. The internal handle is lockable for increased security. The latch automatically deadlocks on closing the door and the snib function (bolt hold back button) enables the latch to be held back. The lock uses a 5 pin high performance