This Yale P77BLX has a hardened case finished in Brasslux and the Cylinder is finished in Polished Brass Pack Type: Visi Pack Supplied with 2 x keys Security Rating: Standard Not recommended for glass panelled doors, unless used in conjunction with a 5 lever mortice lock The Yale 77 Series Traditional Nightlatches are 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.