ScreenRoom 8 ft. x 1 in. x 2 in. White Open Back Aluminum Extrusion The 1 in. x 2 in. Open Back aluminum extrusion The 1 in. x 2 in. Open Back aluminum extrusion attaches to existing posts or walls creating aframefor ascreenwall. Its extrudedscreenchannel accepts flat spline for superiorscreentoughness even in the windiest environments.