Yale standard nightlatch dmg cylinder 40mm backset box
This yale nightlactch is a commonly used latch due to its automatic deadlock and snib functions operated by key from the outside and lever handle from the inside the inside handle can additionally be deadlocked providing even further security please note this latch has a 40mm backset which is the measurment from the edge of the door to the direct centre of the keyhole this smaller size is ideal for narrow or glass panelled doors