3/8" Schedule 80 Thickwall Stainless Steel Pipe, Nipples, Tees, Elbows, and Adapters/Reducers.  NPT Thread.

One piece of 1/4" Hex Connector.

These are New Old Stock from the manufacture of custom pressure washing equipment. 4500+psi rated. Priced per each. Free standard shipping.

I also have two Parker 3/8" inline filters available in separate listings.