kwikSTIK® Paper-Faced Nail-On Metal ½” Bullnose Kerf are used on 90° outside corners with any standard window and door with a standard kerf cut into the frame. Will work with any drywall thickness for smooth, rounded corners. The rigid steel-reinforced corner is covered with a unique, high strength paper providing maximum strength and protection while preventing cracking caused by the movement or shrinkage of framing members. This product utilizes thicker steel that meet ASTM standard C1047. Install by pressing firmly into the kerf and fastening the flange to the wall.