The RAM large 4" rubber suction base mount consists of the 1" dia. ball and socket system with RAM plastic cradle for the Garmin Quest. The rubber suction cup base has a 1.0" dia. rubber ball connected at right angles. The suction cup is designed to hold on any smooth non-porous surface, but for best result, mount the suction cup on a glass surface. The ""U"" in the part number reflects product packaged in poly bag. For additional specifications, see components and drawings tabs.1 Inch Rubber BallBlack Powder CoatPowder Coated Marine Grade Aluminum