They are chair mounts by Interface Dynamics, which sadly are no longer around. It's a platform with a pole on a swivel joint that is metal banded around the front of the arm rest. Then velcro straps to secure the
HOTAS to the platform.
Here are the
Logitech speakers and the mount I built and painted from some housing frame joints:
The cables for the speaker and
HOTAS that I have running off on the left side to the PC:
We just got into a new place, and I've got my own study/PC room now. It's coming together, so here's a more recent pic: