The RAM-B-149Z-UN11U consists of a zinc coated u-bolt base, double socket arm, round base adapter and universal X-Grip® clamping cradle for 12"-13" tablets. Included in this package is hardware that will accommodate rails from 0.50" to 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 0.5". The mount is designed with a RAM 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 X-Grip® clamping cradle consists of a composite spring loaded cradle, expandable grip arms and additional bottom support keeper. Included are extra easy access grip knobs, located on the back of the cradle for quick release of your tablet. The X-Grip® clamping cradle expands and contracts for perfect fit of most 12"-13" tablets with or without sleeves, as well as some smaller tablets. Please verify dimensions of your tablet below for compatibility with the X-Grip®.