RAM 1.5″ x 1.75″ Base 5/16″ Hole & 1″ BallThis Mirror Plate with 1″ Mounting Ball (RAM-B-126C) connects to the back of the RAM Convex Rearvision Mirror (RAM-B-126M) has dimensions 7″ H x 14″ L. The mounting ball allows the mirror to be connected to the RAM Ball and Socket system so you can position the mirror in the optimum viewing location.The “U” in the part number reflects product packaged in poly bag. Ball Size: 1 Inch Rubber BallMaterial: Powder Coated Marine Grade AluminumColor: Black Powder Coat