This is the 3330-17 150mm Leveling Bowl Adapter from Vinten. It is compatible with Osprey, Pro-Ped, Quartz, Quattro Pedestals and HD tripods as well as a Vinten Quickfix adapter. This adapter allows a pan/tilt head with a 150mm base to install on a standard Vinten four-hole base. The leveling bowl attaches to a tripod with a flat base and acts as an intermediary for the tripod to accept video heads with a 150mm-ball base.