Kostiner Archival Washer question

[Greg]

I have a Plexiglass Kostiner Archival Print Washer. See attached image.

This plexiglass adapter came loose with the washer. I have to assume that it inserts into the bottom side of the washer.
Shorter round tune with tiny ID into the washer?
Longer round tube with larger ID to attach the water hose to?
What does the rectangular piece of Plexiglass with the small hole in it do?

thanks