DOT Male Push-In Connector, 5/8 Tube x 3/8 MPT | K.L. Jack
3/8" Tube O.D. x 1/4" MPT Male Connector, Double-Ferrule Stainless Steel - Hi-Line Inc.
LTWFITTING 1/4 in. O.D. Comp x 3/8 in. MIP Brass Compression Adapter Fitting (30-Pack) HF684630 - The Home Depot
Amazon.com: 3/8 Air Fittings Push to Connect Fittings,CEKER 3/8 Inch Tubing Od x 3/8" NPT Thread Male Pneumatic Fittings Air Line Fittings Quick Connect Push in Connectors 5Packs : Industrial & Scientific
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3 4 6 8 10 12mm 1/8 1/4 3/8 1/2 Pipe OD Tee 3 Way Double Ferrule Tube Fittings T-Type 304 SS Stainless Steel Pipe Connector - AliExpress