Does anyone know what this is?
This donut came with my new 5th wheel, grouped with a bunch of items I got for the BBQ grill. It's flat as a pancake, the cap on top is the size of a garden hose and it has a rubber plug under the cap. It's about 2 feet in diameter and no one seems to know what it is. Help?
2014 FR Salem Hemisphere Lite 366BH
2016 Ram 3500 Dually