Most Class A owners go with a Stay-A-While from Mr. Heater... In the old days we went with Extend-a-stay from Marshall brass but it appears MB discontinued that line, Mr, Heater picked it up, appear to be identical
Features:
Propane in from Main tank or reserve (External luggable) tank or with extension hose rented big tank.
Propane out to Motor home regulator OR via a "Quick connect" fitting to a grill or other high pressure propane appliance.
Check valves prevent flow the wrong way through the device (so gas can not flow OUT of an inlet)