With a five-lever mortice sashlock or deadlock, the locking mechanism is morticed into a slot in the door and the strike plate is fitted to the door frame.
Every 5 lever has a latch operated by a handle on both sides of the door and a deadbolt key operated from both sides.
A five-lever mortice deadlock conforming to BS3621 is locked and unlocked by a key from either side, and has additional security features incorporated into its design.