SP25MM17 is a versatile adapter that allows you to convert mounts with a 25mm (1 inch) mounting pattern (including Arkon Robust Mount models and RAM Mounts‚Äîsold separately) to a 17mm mounting pattern. This particular adapter is required to make a Robust Mount Series pedestal compatible with our Mobile Grip 2 holder MG002WR. This includes only the 25mm Ball to 17mm Ball Adapter. (Mounts, holders, and devices sold separately.) Secure the adapter onto any mount accommodating the 25mm (1 inch) ball pattern. Use the SP25MM17 adapter with current Arkon Robust Mount Models including RM080AMPS (Heavy-Duty 80mm Suction Mounting Pedestal with 4-Hole AMPS Head), RM2XAMPS (Heavy-Duty 4-Hole AMPS to 4-Hole AMPS Mounting Pedestal), or RM0802T (Heavy-Duty 80mm Suction Pedestal) to make them compatible for Garmin GPS or other devices with a 17mm mounting pattern.