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: Apple iPhone 4 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