The RAM-118 consists of a double socket arm, 2.5" diameter round base with the universal AMPS hole pattern and large "U" shaped clamp that can strap around a 4" to 6" pipe. Originally designed for strapping to a lantern base, this mount can also be used as a base to strap to a round rail. Material: Powder Coated Marine Grade Aluminium Ball Size: 1.5" Rubber Ball Size Colour Black Components RAM-118B RAM-202 RAM-201