This round 2.5″ diameter round base has seven holes that are compatible with any AMPS pattern accessory. You also have the versatility to mount your device permanently onto your vehicle with this base by using the AMPS holes to bolt your mount down.
Dimensions: 2.5″ diameter
Hole pattern: 1.5″ x 1.88″ AMPS hole pattern and 3 holes at 120 degrees.
Ball size: 1″ diameter (b-size) ball.