Those traps are fairly new to the RV industry and not a lot of people know about them.
The best thing about them is you don't have to remember to winterize them.
The RV mfg's like them because they don't have to install a dedicated vent for the fixture, so it saves them a little time and space.
Salem 29RKSS Pushing a 2500 Mega-Cab CTD!
Gotta go campin!