The Yale 89 series deadlocking standard night latch security locks are some of the most widely-used front door latches They are key operated from the outside and lever handle operated from the inside The latch automatically deadlocks on closing the door and the snib function (bolt hold back button) enables the latch to be held back The inside handle can also be deadlocked by a reverse turn of the key in the cylinder giving additional security (when deadlocked in this manner the latch cannot be opened from the inside only from the outside with the key) The 89 series security night latches have a 60 mm backset--this is the measurement from the edge of the door to the center of the keyhole Locks with a 40 mm backset are normally used where there is restricted space, such as on a narrow glass paneled door This Yale P89DMGPB has a hardened case finish in dark metallic grey and the cylinder is finished in polished brass Inside handle can be deadlocked by a reverse turn of the key in the outside cylinder after closing the door