These are non-rotating adjustable eyeiece holders for the AP/Baader/Zeiss binocular viewer. These custom made eyepiece holders are meant to replace the original fixed eyepiece holders and allows you to adjust each eye separately in case your eyes are different, or even if there is a small difference in your eyepieces. They also allow you to use the longer-barreled eyepieces like the TeleVue Radians in the binocular viewer. They were manufactured by an engineering firm that made the sample collector that will be flying to Mars on an upcoming mission so you can know that they do very fine work.
These holders are non-rotating which means that the eyepiece will go up and down without rotating or turning. I have 1 set available and they will probably not be made again since the manufacturer requires a minimum of 20 sets to do the run. The cost is $450 and this includes packaging, insurance, and shipping. Complete installation instructions will be included along with the 2 required allen wrenches and all necessary mounting screws. These holders were specifically designed to only work in the AP/Baader binocualr viewers and the older Zeiss models of identical design.
After you place the eyepieces in the holders they lock securely in place with brass locking rings so no marring will occur. You then adjust up and down by twisting the etched adjusting ring (easy to grab because it is wider than the holder) while viewing through the eyepiece. Perfect focus in both eyes can then be obtained.