RAM Composite Double Ball Mount for Humminbird, Matrix + More (RAP-107U) (sku 54473)The RAP 107U consists of a composite 2. 5" diameter round base with the universal AMPS hole pattern, composite double socket arm, and connecting Humminbird Apelco marine adapter base. The mount is designed with a RAM 1. 5" diameter patented rubber ball and socket system that has adjustment points at both ends of the double socket arm; thus allowing for almost infinite adjustment and perfect viewing angles. Height: 7. 35" SOCKET TO SOCKET LENGTH 4. 66"