The RAM-B-149Z-UN8U consists of a zinc coated u-bolt base, double socket arm and universal X-Grip clamping cradle for 17.78cm (7") -20.32cm (8") tablets. Included in this package is hardware that will accommodate rails from 1.27cm (0.50") to 3.18cm (1.25") in diameter. The base includes black cover caps to be placed over the exposed ends of the u-bolt. The included composite rail adapter can narrow the rail to a minimum width of 1.27cm (0.5") . The mount is designed with a RAM 2.54cm (1") diameter patented rubber ball and socket system that has adjustment points at both ends of the double socket arm; this allowing for almost infinite adjustment and perfect viewing angles. The spring loaded X-Grip cradle expands and contracts, allowing for a perfect custom fit of your 17.78cm (7") -20.32cm (8") tablet. Included are extra easy access grip knobs, located on the back of the cradle for quick release of your tablet. The X-Grip includes a device tether recommended for outdoor applications. The cradle is compatible with handheld devices that will fit the dimensions listed below. It is important to verify the dimensions of your handheld device with a case/sleeve/skin when determining the overall size.