Zacuto 19mm Q-mount
Zacuto's universal Z-Release mount for 19mm studio rod systems can be installed anywhere on your rod system without removing any equipment; it attaches by mounting underneath the rods and tightening the outer levers. The Q-mount 19mm studio has many uses including: mounting Zamerican arms for monitors, lights, harddrives, etc, other arms with Zacuto Zuds (available in 3/8 16" and 1/4 20" both male and female) or 15mm rods.
The Q-mount can also be used to create a lens support, check out Zacuto's Locking Lens Support.
More information about Zacuto Products (Link to Zacuto Website)