The Rock Solid Tripod Cross Bar from Tether Tools allows the user to create a custom, mobile tethering workstation by supporting both your camera and a Tether Table Aero on top of the same tripod - or similar support. The cross bar mounts directly to most supports via a central 3/8"-16 thread but can also mount to a heavy-duty lightstand with the use of a Rock Solid Baby Ballhead Adapter.

The cross bar features four separate mounting points, each one equipped with a 3/8"-16 thread for compatibility with most tripod heads and Tether Tools accessories. The two horizontal mounting points can be shifted along the cross bar for custom positioning and feature knurled screw plates for easy and rapid mounting and dismounting of equipment.

https://www.bhphotovideo.com/c/product/1222491-REG/tether_tools_rstaa4_rock_solid_tripod_cross.html