What does this part in the hitch work?

[UltTrail runner]

This is part number PT228-00380, and I am planning to install it to my in bumper hitch receiver. anyone know what is the function of the ring and where it should go?

 

[badlander]

Probably just a spacer for a ball bolt smaller than the hole in the hitch bar so the ball doesn't slide around and loosen up.