Bulkhead Fittings Size:4" FNPT x FNPT this is done by using

this is done by using a bellow design that has very little resistance

Oxygen Accessories

Robust Aire Diffuser Assemblies with weighted base

no specific alignment is necessary

or it can be used with the optional PVC stand

Bulkhead Fittings Size:4" FNPT x FNPT this is done by usingDescription These female threaded bulkhead fittings are great for most bulkhead applications. Made of polypropylene, they are similar to, but softer and less brittle than the PVC bulkhead fittings. Since these are made of polypropylene the side fitting are more robust which is great for installation but also means they are not as low profile as some of our other bulkheads. Price includes one EPDM gasket. Specs More Info Size Hole Saw Size Max Tank