Zinc coated U-bolt base, double socket arm and round base adapter Adapter has a hole pattern that matches the industry standard AMPS hole pattern Includes hardware that will accommodate rails from 0.50" to 1.25" in diameter A composite rail adapter can narrow the rail to a minimum width if 0.5" Mount designed with a RAM 1" diameter patented rubber ball and socket system that has adjustment points at both ends of the double socket arm