The APPLAMPS25 25mm ball to 4-Hole AMPS circular plastic adapter is compatible with 25mm (1 inch) mounts and pedestals, including those from Arkon or RAM Mounts. (Mounts, holders, and devices sold separately.) The sturdy plastic adapter can be drilled into dashboards or other solid, flat surfaces, and is ideal for commercial or fleet use. The circular design is a great alternative for locations where a square adapter won't work.