What is this?
The top “valve/connection”?
Some RVs have a built-in RV black tank flush system, which allows you to connect a hose directly to an inlet valve to essentially power wash your tank. … This rinser is designed to spray water in multiple directions, in order to clean debris and tissue from the sides of your RV black water tank.
That is a water filter wrench, look for your RVs water filter system, that is the tool to help you get it off to change the filter.
Next up who knows 🙂