I originally designed, manufactured, and sold the non-rotating adjustable eyeiece holders for the AP/Baader/Zeiss binocular viewer. I was recently selling what I thought was my very last set and the manufacturer had to remake 3 new parts, so he went ahead and made 3 complete sets. There are just 2 last sets available. 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. After you place your eyepieces in the holders they both LOCK in place with brass compression rings so there will be no marring. You focus with your right eye open using the telescope focuser, then with only your left eye open, you adjust the left side with the turning diopter adjusting ring. Then open both eyes, and whala.
The adjustable eyepiece holders are extremely smooth in operation. These holders are non-rotating which means that the eyepiece will go up and down without rotating or turning. These sets will probably not be made again, and and the cost is the same $450 + $10 (for packaging and shipping) that I sold all of the other ones for. 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.