Arkon's SP25MM38 adapter allows you to connect and extend mounts and pedestals with a 25mm (1 inch) ball mounting pattern to a 38mm (1.5 inch) ball mounting pattern, or vice versa. This adapter can be used with 25mm or 38mm ball compatible double-socket Robust Mount Shafts and other Arkon Robust Mount models, as well as 25mm or 38mm mounts and pedestals from other manufacturers, such as RAM Mounts Size B or Size C (sold separately). Mounts, holders, cradles, and devices are sold separately. Use the adapter on any mount or pedestal accommodating a 25mm (1 inch) or 38mm (1.5 inch) ball pattern.