The RAM-101U-247-3 consists of a double socket arm, round 2.5" diameter round base with the universal AMPS hole pattern and 3" square rail clamp base. The square rail base will wrap around a maximum width of 3" and is tightened by screwing the two plates together with the included nuts and bolts. Rubber ball, socket technology dampens shock and vibration, as well as allows for almost infinite adjustment, perfect viewing angles.