The RAM 4" large rubber suction base mount consists of the 1" dia. ball and socket system with RAM Plastic Cradle for the Garmin eTrex Series. The rubber suction cup base has a 1" 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. Part number reflects product packaged in clear clam shell for store shelf display. For additional specifications, see components and drawings tabs.Powder Coated Marine Grade Aluminum1 Inch Rubber BallBlack Powder Coat