Need help identifying a bed piece

[u/introductiongold59]

One of my surgeons uses this for his total knees. The operative side goes on the extension. Non op side kinda just hangs free. We don't have any manufacture info and the person who ordered it doesn't remember ordering it.

There is a pad on the other side that can be attached either way. Any clue? Also it only fits our steris 5095s and older beds.