The yale 77 series traditional nightlatches are the the original yale lock with classic styling the deadlocking snib function enables the latch to be held back or deadlocked internally the nightlatch is key operated from the outside and has a knob handle for operation from inside the 77 series nightlatches have a 60mm backset this is the measurement from the edge of the door to the centre of the keyhole supplied with 1109 external cylinder