Nylon Rail Mount with Knobs for 7/8" to 1" Railing - 1" - #14 ThreadRail swivel mount in anti-yellowing reinforced nylon. Design with knob locking and GPS hole for an easy, fast anbd safe installation on vertical or horizontal rails of 22mm (7/8") and 25mm (1"). Not for use with antennas longer than 2,4m (8') in self supporting mode. Standard 1"x14 thread. WARNING: This product can expose you to chemicals including LEAD which is known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.