The overall height of the antenna base: 4.1 inch (105mm); Mounting flange diameter: 2.8 inch (71mm); Thread outer diameter: 1"-14 threaded mount;Thread length: 0.65 inch | The antenna base is made of stainless steel 316, resistant to seawater corrosion, and can replace plastic or nylon materials | The surface of the antenna base is mirror polished. Smooth and beautiful, no burrs on the thread | Designed to allow antenna wire to feed directly through the base eliminating the need for a separate cable grommet.Ideal for TV, Loran, GPS and VHF antennas with standard 1" threads | Packaging: There are two kinds of screw fittings for your choice, one is the bolt, the other is the screw (All accessories are made of 316 stainless steel)