The RAP-B-107B-354-TRA1U consists of a Track Ball base, composite double socket arm and connecting Humminbird/Apelco marine adapter base. The mount is designed with a RAM 1" diameter rubber ball and socket system that has adjustment points at both ends of the double socket arm - allowing for high adjustability to achieve perfect viewing angles. This kit is compatible with virtually any track system including the RAM Tough-Track. T-Bolt Dimensions: .48" x .95"