What is the difference between the Standard Mortise box and the UL listed box?
The standard Mortise box has buttons on the edge of the door that allow you to set the box to lock behind you as you leave the home, or another button to keep the door unlocked. This button setting is reset each time the door is locked.
The UL Listed Mortise does not have the buttons on the edge of the box. This set will only lock when locked with a key outside or thumbturn inside. This is also a UL listed box unlike the standard set.