The base consists of a 1″ diameter rubber ball, hardware for mounting to both brake/clutch reservoirs and rails that are 0.5″ to 1.25″ in diameter. The mounting hardware for brake/clutch reservoirs include both standard and metric mounting bolts. Multiple pivot points, rubber ball and socket technology allows for almost infinite adjustment and perfect viewing angles. High quality materials insure your device is safe, secure, and within easy reach. This mount is designed to hold the following devices: Garmin nuvi 300 Garmin nuvi 310 Garmin nuvi 350 Garmin nuvi 360 Garmin nuvi 370 Included with Purchase: (1 qty) High strength composite cradle (1 qty) Base/ball adaptor (attaches directly to cradle) (1 qty) Standard size double socket arm (1 qty) Mounting base (mounts to either brake/clutch reservoir or rail/handlebar) Hardware for mounting to either brake/clutch reservoir or rail/handlebar Material: Powder Coated Marine Grade Aluminum and High Strength Composite Ball Size: 1″ Rubber Ball „B” Size Note: *The RAM-B-174-GA21U can mount to both the brake/clutch reservoir or any round rail that is 0.5″ to 1.25″ in diameter. The „U” in the part number reflects product packaged in poly bag. To see if the RAM-B-174-GA21U base will mount to your motorcycle, check the hole spacing of the base against your clutch/brake reservoir. The holes centers have a minimum width of 0.94″ and a maximum of 1.58″. Related Links:RAM Motorcycle Mounts Page RAM GPS Mounts PageBrake/Clutch Reservoir Base Assembly Instructions. RAM® double socket arms with their distinctive hour-glass shape are designed and recognized to provide the best possible performance for most any application.