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. Classic design nightlatch. Lock is immediately engaged when the door is closed. Suitable for use on wooden doors up to 57mm thick. Includes two keys & fittings. Standard 60mm backset. The Yale Nightlatch is a classic design that has set the standards in convenient door security for over 70 years and is trusted by millions. Although typically used for exterior wooden front doors in conjunction with a mortice deadlock, the Yale nightlatch is commonly used for interior bedroom doors in shared houses with multiple occupants where additional security is required. The internal knob and snib button provides a convenient way to operate the lock from inside the property. The latch bolt is immediately engaged as soon as you close the door and can also be held back temporarily with the snib button. The internal knob is used to operate the lock from the inside and can be deadlocked by the snib button for additional overnight security. The external five pin rim cylinder lock is manufactured to a good specification, is tested for resistance to corrosion and a minimum of 100,000 usage cycles. If upgrading an existing unit you should be able to use the holes that are already on the door. Available in standard (60mm) and narrow (40mm) backsets, and brass, chrome and traditional green finishes.