1Applicable Rails: Base measures standard 1?14in male thread, recommended for installation on 22?25mm (7/8?1in) vertical, horizontal or oblique rails. 2316 Stainless Steel: Constructed corrosion resistant investment cast 316 stainless steel, has good wear resistance in humid air or high temperature weather. 3With Lever Handle: This ratchet rail antenna base features a lever action handle that makes lowering the antenna quick and easy for passing under trailering. 4Adjustable Ratchet: The antenna base has 2 adjustable ratchets, the upper ratchet can be adjusted to 270 degrees, the lower ratchet can be adjusted to 180 degrees. 5For Marine Use: The Vhf antenna mount is suitable for boats, yachts, RVs, etc., it has a compact structure and standard size, which is easy to install and replace.