Amazon.com: KOOTANS Forged Brass Equal Hex Nipple, 3/8'' NPT Male x 3/8'' NPT Male Thread Adapter Brass Pipe Fittings Connector Couplings (Pack of 4) : Industrial & Scientific
Amazon.com: KOOTNAS 2-Pack Solid Brass Bulkhead Fittings, 3/8 NPT Taper Female 1" Straight Male Thread Brass Connector with Metal Wave Ring, 1.32" Length Brass Coupling Fitting : Industrial & Scientific
1/2 to 3/8 Reducer Faucet Adapter - Compression Brass Pipe Fitting, 3/8 Male to 1/2 Male Supply Line Adapter for RV Kitchen Plumbing, Water Hose Pipe Connector with Rubber Washer, (2 Pack) - Amazon.com
Merit Brass - Brass Pipe Reducing Coupling: 3/8 x 1/4″ Fitting, Threaded, FNPT x FNPT, Class 125 - 02204139 - MSC Industrial Supply
Amazon.com: KOOTANS 1/2 NPT x 3/8 NPT Male Solid Brass Hex Nipples, Heavy Brass Pipe Adapter Fittings Reducing Nipple Connectors 4Pieces : Industrial & Scientific
Brass, 3/8 in x 3/8 in Fitting Pipe Size, Coupling - 46M498|706103-06 - Grainger