This screw is designed specifically to insure proper installation of vinyl retrofit windows. The metal cutting tip will drive through the vinyl side jamb, the existing aluminum frame and the framing material. Once the recess below the head of the screw grabs and holds the vinyl window side jamb, the window can be plumbed in the opening and a proper reveal can be achieved between the side jamb and the sash. The powder coated head will add to the look of a secure and professional installation. T25-1" bit included.