Yale'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 cylinder, and has a 20mm bolt which is anti-carding. It also has a 2 year guarantee. The P1 double security nightlatches have a 60mm backset, this is the measurement from the edge of the door to the centre of the keyhole. Locks with a 40mm backset are normally used where there is restricted space, such as on a narrow glass panelled door. Supplied with 1109 external cylinder. Case Width: 60mm Case Height: 88mm Case Depth: 30mm.