All diffusers regardless of whether they are ceramic, rubber membrane or other type of material should have a back flow valve to prevent water from entering your airline. If you do get water coming back up your airline it can cause compressor issues as everytime your compressor has to restart, it has to first push the water out of the airline which requires extra pressure. Secondly water in your airline can freeze during the winter months, which means no air comes out and you put undue pressure on your compressor, which can burn up motors and/or break crankshafts and pistons quickly.
This backflow valve comes with 1/2" female NPT threads on the lower end. Please let us know in the comment section if you need an adapter for 3/8" threads and we'll supply that at no extra charge. The hose barb end fits 3/8", 1/2" and 5/8" airline and attaches to both weighted and non-weighted airline with an included stainless steel hose clamp.