The Zacuto T-Mount Rod Adapter mounts a 15mm rod of a camera rig and adapts a rod-mounted accessory, such as a mic, onto the rig. T-Mount is T-shaped and features a rod opening on top and another on the side. One is for mounting and the other for adapting. One tightens by Allen screw, the other by lever for quick-release use.
T-Mount's most common use is to attach a Sony FS100 mic to a Zacuto FS100 Top Handle. Another common one is to attach Zacuto's Articulating Arm. But you can do pretty-much anything you can think of with two 15mm rods...(one of the openings has a bottom, the other goes through from end to end).