This is a roller only and is used on bottom mount installations. It is a 1-1/4 in. high density polyethylene roller with a 3/8 in. axle hole. The high density polyethylene roller has a narrow offset groove. It comes with a 8-32 threaded bushing and screw that inserts into 9/32 in. roller axle hole. When installing, the screw installs through the screen frame and into the threaded bushing and roller. The opposite side of the screen frame will hold the threaded bushing in place. Color: Aluminum.