The RAM 4″ rubber suction base mount consists of the 1″ dia. ball and socket system with RAM plastic cradle for these Garmin GPS. GPSMAP 176GPSMAP 176CGPSMAP 196GPSMAP 276CGPSMAP 296GPSMAP 396 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.