Using strategically placed screws, the APCMAMPS57 circular metal 57mm ball to 4-Hole AMPS adapter can mount onto dashboards or other surfaces. It will work with both commercial and fleet vehicles. Perfect for installation into vehicles, this adapter is compatible with any Arkon or RAM mounts product. The APCMAMPS57 circular metal 57mm ball to 4-Hole AMPS adapter provides sturdy metal construction that’s perfect for commercial and fleet vehicles. The round design is a great alternative for locations and devices where a square adapter won’t work.