This powder-coated, marine-grade aluminum Humminbird mount consists of a short length double socket arm, a 3.68" diameter round base with a 2.25" D size ball, and one 1.5" x 4.5" rectangular plate with a 2.25" D size ball. The round plate contains two mounting holes at 180-degrees and three mounting holes at 120-degrees. The 1.5" x 4.5" rectangular plate contains a 4-hole pattern compatible with Humminbird 8, 9 & 10 models. The rubber ball and socket technology provides shock and vibration damping, and allows for near-infinite adjustability so you can position your device at the perfect viewing angle.