2.25’’ ball round base features industry standard 4 hole AMPS pattern that will work with all industry standard AMPS adapter plates and vehicle specific mounts. Circular plate features industry-standard AMPS hole pattern and measures D3.7", connects to 2.25’’ mounts device holders containing the universal AMPS hole pattern Included D size 2.25" rubber ball allows for connection to any D size double socket arm; ball and socket technology allows for near-infinite adjustability Compatible with RAM and 2.25" Ball Systems from Arkon, iBolt and Tackform or any other 2.25 inch / 56mm / D size industry standard compatible mount. Made of powder-coated, marine-grade aluminum and high-strength composites for durability and reliability in the most demanding environments Backed by a lifetime warranty Backed by a lifetime warranty.