Want a cunning plan for fitting these? Fit the non bally bit to the frame of the locker. Then back off the spring retaining screws in the bally bit so that it just holds the non bally bit. Put some double-sided tape on the back of the bally bit, and locate it on the non-bally bit. Shut the door, and when you open the door again the bally bit will be stuck to the back of the door in the right place.