Glomex Nylon Rail Mount w/Knobs f/7/8" to 1" Railing - 1" - #14 ThreadNylon Rail Mount with Knobs for 7 8" to 1" Rails 1" 14 Thread Rail ratchet mount in reinforced nylon UV resistant design with knob and hole for GPS. Easy installation on vertical or horizontal rails of 7 8" (22mm) and 1" (25mm). Usable with antennas no longer than 8' in self supporting mode. Standard 1" x 14 thread. WARNING: This product can expose you to chemicals including LEAD which is known to the State of California to cause cancer, birth defects