The RAM-B-121-238U consists of a yoke clamp base, standard length double socket arm and 2.43" x 1.31" diamond base. The yoke clamp base will fit rails in diameter from 0.625" to a maximum of 1.25". The 1" rubber ball is at a right angle to the plane of the mount when connected to a rail, the ball sits parallel to the rail. The diamond base has two holes 1.912" from center to center, matches the industry standard AMPS hole pattern and will connect to a large variety of RAM Mount and third party cradles. The mount is designed with a RAM 1" diameter patented rubber ball and socket system that has adjustment points at both ends of the double socket arm, allowing for almost infinite adjustment and perfect viewing angles.