Amazon.com: Hooshing 3/8" Male to 3/8" Male NPT Hex Nipple Stainless Steel 304 Threaded Pipe Fittings for Brew Kit Home Piping, Pack of 4 : Industrial & Scientific
1/2" Tube O.D. x 3/8" NPT Male Connector Fitting – Alabama Industrial Products
USA Industrials - Pipe Reducing Hex Nipple: 3/8 x 1/4″ Fitting, 316 Stainless Steel - 96968540 - MSC Industrial Supply