The RAM-B-202 RAM marine grade aluminium base contains a 1" diameter rubber ball connected to a flat 2.5" diameter base. This mount has pre-drilled holes, including the universal AMPS hole pattern. Material: Powder Coated Marine Grade Aluminium Ball Size: 1" Rubber Ball "B" Size TIP: If you have an old Garmin 2610 Streetpilot and want a RAM mount, the RAM-B-202 fits onto the Garmin holder. Then add an arm and base to complete your mount.