These Plexidor Slider Tracks allow the metal cover to be slid in and out very easily for day to day use instead of screwed into the frame
The cover actually screws to the pet door frame, so in order to attach it you have to get down on hands and knees with a screwdriver to put it on. This is probably the most secure cover of any pet door on the market, but it is not the most convenient method for locking a pet door. The Plexidor Slider Track for Locking Cover allows the cover to be slid into rails on the sides of the pet door. This is a good upgrade if you plan on using the steel cover for the dog door on a daily basis. The cover does have to go in from the top so this may not work if the pet door is installed in a wall under a window with a sill or under a cabinet, etc.