20535 NEWS Adapter
These basically allow you to mount any of our probe are holders at 90 degrees from a normal mount on a positioner or translation stage. This could provide you with a North, East, West and South facing probe. You can mount off of either side of the 20535 part.
Photo's show's mounting suggestions on an XYZ 500 MIS. Mounted on the NEWS adapter are part numbers 20508 and a 20504.