This Yale nightlatch lock is the more modern version of the traditional nightlatches featured elsewhere on our site, with the added feature of a double locking mechanism
The double locking mechanism operates by putting the key in the outside cylinder upon exit and turning in the reverse direction
This will double lock the handle on the inside, stopping a thief breaking the glass and letting themselves into the property
Careful consideration should be given when fitting this Yale nightlatch lock to give the building occupants clear instructions in use, as it is possible to lock someone within the property if the handle is double-locked with an occupant still inside. Not therefore recommended on single entry / exit door dwellings
Backset is measured from the edge of the door to the centre of the keyhole