This product is made of marine grade 316 stainless steel which is more rust and corrosion resistant than 304 stainless steel, made to withstand the harsh salt water environment. This antenna base features an adjustable axle that allows 180 degrees of adjustments. This product can be fitted on boats, yachts, and other water vehicles. Dimensions: Length 4-1/2 inches; Base Diameter 2-13/16 inches; Fastener 0.212 inches (5.4mm). Package includes one MARINE CITY 316 grade stainless steel 180-degree adjustable swivel tall antenna base, does not come with the screws for mounting.