Extra camera plate base assembly for the 322RC2. Using the 322RA allows you to choose whether to mount your camera in the low center of gravity position unique to the 322RC2 head, or in the "upright" position formerly used by the 222 head. The advantage of the upright position is that, although the camera weight is more off-balance on the head, you can use your strongest fingers to operate the 322RC2 trigger, so it may feel more stable to you.