RAM twist lock, suction cup mount, designed to hold the following TomTom GPS units:GO 520, 520T, 720, 720T, 920 & 920TThe suction cup is designed to hold strong to smooth non-porous surfaces. For best result, mount the suction cup to a glass or non-porous plastic surface.TomTom GO 520, 720 & 920 Product Feature PageRAM GPS Mounts PageRAM Suction Cup Mounts Page 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 AluminumBlack Powder Coat1 Inch Rubber Ball