The Seaview 316 S.S. Rail Mount is designed to fit 1", 1 ⅛” and 1 ¼” rails and is for mounting GPS, weather or VHF antennas. Cast of solid 316 stainless steel and comes with three different rubber bushings. The unique two-piece design clamps to a rail and keeps wiring completely hidden inside the mount and railing. The 1"-14 threads accept most common GPS or VHF antennas.