Perfect Axis Wake A22 Check Valve
I bought a 2013 Axis A22 with Plug and Play and what do you know... Axis forgot to install check valves at the factory. I placed one of the Fly High 1-1/8" check valves on all of my fill lines and I don't have any issues with passive draining. They are easier to install and way less expensive than the Vented Loops like Malibu uses.