Shakespeare Style 4720 Economy Rail Antenna MountShakespeare's Style 4720 Economy Rail Mount is designed for quick and easy installation on vertical or horizontal, straight or angled rails. Its simple design makes installation a snap. The vice section grips the rail, and the flat section supports the antenna. The flat section can also be bolted to a flat surface, instead of to the rail grip.Standard 1" - 14 threadNylon adapters included for 7/8", 1", and 1-1/4" vertical or horizontal railsStainless steel construction