I went through all the work of replacing this with a 1/2" PEX "Sharkbite" copper check valve, that I found at the local Ace hardware when I was in West Yellowstone, Montana. For some reason the RV plumbing codes require that this atmospheric breaker/check valve needs to be located above the highest drain in the bathroom. Yet you can buy add-on black tank sprayer systems at RV parts stores that don't even HAVE a check valve. There is some inherent protection just in the fact the sprayer sprays into an air space in the black tank, but I feel better having a check valve between any connection to a black water system and a fresh water system.
BTW, my plastic valve blowing apart under high water pressure took out the $250 battery charger/converter underneath this check valve line.