The RAM-B-309-3U ball connects to the open hole on the side of the RAM-B-309-1U (single 1" ball) and is included with the purchase of the RAM-B-309-2U (double 1" ball).
Note:
*The RAM-B-309-3U ball is for extension mounts to the RAM Chrome Motorcycle Brake/Clutch Reservoir Base (RAM-B-309-1CHU)
