My LTV Unity had Hepvo traps. Work really well.Here is something I didn't know and learned today and it is kind of good news. A discussion came online about a waterless plumbing trap or no need for a standard P trap you have to keep filled with water to prevent sewer odors from coming back through. Advanced RV saw the discussion and let me know they have been using the waterless trap in their RVs. It is called a Hepv0 trap that works on the principle of a collapsible one way valve that will allow flow in one direction. This will eliminate the problem of traps drying out in storage or sloshing out on the road. It will also eliminate the need to put the pink antifreeze in your traps when winterizing. And it saves space under a sink where you might want to store stuff. To be honest, I had never heard of it until the discussion came up.