Used Hy6/AFi digital back to Sinar P/P2/P3 adapter
This plate allows you to fix your AFi or Credo or Sinar digital back in Hy6 mount to a Sinar lens board for the P system. Thereby allowing you to use your digital back on their excellent view camera with geared movements for complete perspective control. The Sinar P2 is stronger and perhaps more capable than the X-Act2 and will have more bellows options, particularly for longer lenses.
I actually have never seen another one of these so they can't be too common.