The RAP-B-238-BU consists of a 1" diameter rubber ball connected at right angles to a 2.43" x 1.31" diamond base. The base has two holes 1.912" from center to center, matching diagonally with the industry standard 4-Hole AMPS hole pattern. Included with this base is a highstrength composite backing plate, connected with stainless steel screws and nuts for reinforcing any flat surface that the ball is mounted against.