The fixed piers were an optional accessory on the 4″, 5″, and 6″ Polarex and Unitrons. Attached are photos of all three for comparison. The side view is to demonstrate that there are a couple of noticeable differences between the 4″ and the 5″ fixed piers. Most notable is that the 5″ fixed pier is boxier than the 4″. While not perfectly square, the 5″ fixed pier has less of a taper top to bottom. The doors on the piers are the same on the 5″ and 6″ but mirror imaged (as in opposite sides) on the 4″ fixed pier. The 4″ and 5″ fixed pier bases are interchangeable. Photos courtesy of a private owner.
