The RAP-SB-187-UN4 consists of the RAM EZ-Strap base, double ball SHORT arm, diamond adapter base and universal Finger Grip cradle. The strap can be cut to fit tubing, square rails and irregular shapes from 0.5″ to 2.58″ in diameter. Multiple adjustment points allow you to move the mount to your optimum viewing position. This mount rotates 180 degrees. The RAM Composite Universal Finger Grip cradle is designed to hold a large amount of cell phones and electronic devices. The cradle comes with (3 sets) of four flexible rubber coated fingers placed along sides to grip your device. The fingers open by squeezing the ends to open the small finger arms. The bottom of the cradle includes a back plate that adds support to the device being held by the mount. The spine plate contains the universal AMPs and 1.5″ x 2″ hole patterns. Rail Dimensions: 0.50″ to 2.58″