Security Boss Pet Door use a unique flap attachment method that utilizes a two-piece thumbscrew. These thumbscrews have dual function. They secure the flap to the pet door frame and stabilize the flap in position. No reinforcement bar is needed with these attachments. They simply insert into the holes of your replacement flap and cinch together on the pet door frame. You will notice that the black knob is knurled so that it is easy to turn and tighten with your fingers. There is also a HEX head that accepts an Allen wrench (9/64"), so that you can tighten firmly the thumbscrew once in place.

Ensuring that the flap attachment thumbscrews are very tight is important. If the thumbscrews are not very tight, they may work loose and allow your flap to move. This movement can result in the flap tearing through time. We recommend that periodically you check to ensure that the flap thumbscrews are tight to eliminate and problems. The method of attaching flaps on the Security Boss doors was designed so that it is easy and accessible for the customer to not only replace flaps when needed, but also be easy to maintain to eliminate unnecessary replacements.

Note: Thumbscrews are not included when ordering replacement flaps for Security Boss doors, the thumbscrews that came with your door are made to be used with any new replacement flap changes.