Wild describes that as a Phototube A for a monocular camera assembly: to take pictures or movies, or to view in 2-D on a video monitor or screen. (It creates what is often called a "video microscope".) That would not work for me, because I also need to observe and work on things in 3-D and would be constantly removing and installing the photo tube and the stereo viewing head.
I am guessing you might want a Phototube HU or HV: to create a three-tube microscope that lets you easily observe in stereo and take pictures and/or movies. The HU lets do either one or the other, with a quick flip of a switch; the HV lets you observe in 3-D and document/present in 2-D, simultaneously. Is either of those also a requirement for you?