RAM C Size 1.5" Ball Rail Mount with Double U-Bolt Base & 2.5" Round Plate AMPs Hole PatternThe RAM-101U-235 consists of a double socket arm, one round 2.5" diameter round base with the universal AMPS hole pattern and stainless steel double u-bolt base that will fit pipes from 1" to 1.25" in diameter. Designed into the mount is a 1.5" diameter patented rubber ball and socket system with adjustment points at both socket ends of the arm. Rubber ball and socket technology allows for almost infinite adjustment and perfect viewing angles.