The genius EMS systems invented and produced by Tatsuro Matsumoto are the central part to build binoscopes|
EMS means Erecting Mirror System and these systems are available in different sizes for different telescope projects. Here you can see the model EMS-UXL, which I am using for my binoscopes: One special thing of the EMS is, that they are showing an upright and right sided picture, just like binoculars. This makes the orientation at teh sky way easier and thes binoscopes can also be used for daylight exploring.
Other than with other solutions an EMS has only two mirrors instead of three. This means less light loss caused by reflections.
Also the light path is shorter for this diagonal path though these EMS as it is while using three mirrors and 90° reflections. This short light path is important when you are building SCT binoscopes because you can keep the needed backfocus a low as possible. Here is the link to Tatsuro Matsumoto's website