The Rail Mount Fixed Antenna Base is constructed of corrosion resistant formed 304 stainless steel.Includes UV stabilized injection molded nylon mounting brackets for use on 7/8″ and 1″ tubing. Can be mounted on either vertical or horizontal rails as well as any flat surface. Design allows antenna wire to feed directly through the base. Ideal for Loran, GPS, and CB antennas with standard 1″-14 threads. Not recommended for whips over 8.