Short backset, swing bolt deadlocks suitable for narrow stile hinged doors. Positive action deadbolt locked or unlocked by either key, turnknob, escape turn or handle. Suitable for sliding doors where lock can be mounted to door jamb and deadbolt engages strike mounted to face of door. Suitable for heavy duty use in industrial and commercial buildings, institutions, clubs, schools, hospitals, hotels, retail and similar buildings. All 3540 Series Cylinder Mortice Locks are built of the finest materials, with the easy action and solid feel of the world's finest locks.