Selling & Lock bars for over 45 years. Lock bars move up and down on the inside of the door and latch on to a frame hook which is part of the frame of the door. A locker handle is on the outside of the locker which connects to the lock bar which releases the door from the frame of the locker when you pull up on the handle. There are many manufactures of lockers and types of lock bars. Make sure when ordering you are selecting the correct length lock bar.
Robert Brooke Locker Parts Catalog