These two items are used to mount a Rotoscan Cable Chain
http://www.thingiverse.com/thing:11978 hanging from the upper beam down to an AO Pillow X-End
http://www.thingiverse.com/thing:15492 (presumably the motor mount). Derived from my Windbreak/Wall clips. So far it has performed well. Seeing the full photo of the installed version is probably easier to understand than the written instructions.