Mortice Dead Locks are designed to be fitted into the door and to throw a bolt into a keep in the frame, by using a key. They are normally either 3 or 5 lever locks you need to consider a BS 3621 5 lever Dead Lock on all external doors and Three Lever Dead Locks on Internal Doors.

Mortice Sash Locks are extension to the Mortice Dead Lock where a latch would be included within the lock case and these types of locks normally work with Handles that have key holes as well. The latch is designed to hold the door into the frame and the dead lock to throw the bolt into the keep to secure the door into place.