This is UNITRON’s rotary eyepiece selector which holds six eyepieces, any one of which can be rotated into position when needed. It was introduced in 1955 and sold with a cabinet and clamping device.
There are several variations of the UNIHEX. The 1956 catalog indicated a Standard UNIHEX that came in a Model A and Model B. The Model A had the 5 – .965′ and 1 – 1 1/4″ eyepiece holders and the Model B had the 1 1/4″ holders. The Super UNIHEX could accommodate the 40mm and the 60mm eyepieces on the Super Rack and Pinion focuser. Shown here is the Super UNIHEX on the left and the Standard Model A UNIHEX on the right.
Some photos of a Standard Model B Courtesy of Stephen Brennan:
A Unitron Super Unihex Courtesy of Stephen Brennan:
This is a Standard Model B on a UNITRON Model 530, 5 Inch fixed pier Photo-Equatorial that accommodates six 1 1/4″ eyepieces. The owner, Will Thornton, has since upgraded to the Super UNIHEX, shown in the second photo.
Some additional Unihex photos provided by Tore Engen:
Stefan Thiele provided this photo showing the parts breakdown for cleaning the Unihex accessory; “The Unihex can be easily serviced. Fresh grease will work wonders. Oh, the quality! Why don´t they build stuff like they used to” :