A lock assembly for locking one member, such as a door, to another member, such as the frame, comprises a stud unit and a lock unit which can be locked on the stud by means comprising a slide which is engaged between the stud and a surface in the lock unit, a locking ball which extends through an opening in the slide into either a recess in the stud to prevent separation of the units or a recess in the lock unit, which allows such separation, a catch for holding the slide locked and a key-operated lock for releasing the slide.