Parker - Barbed Hose Fitting: 7/16-20" x 3/8" ID Hose, Male Connector - 80258544 - MSC Industrial Supply
ATITOWEL Pack of 5 6mm Brass Hose Connector - G 3/8" Female Thread for 1/4" Hose ID : Amazon.de: DIY & Tools
Reducer Reducer 1/4-Inch RH G 3/8 Lh Female x Male Thread Adaptor Coupling Propane Left Thread Right Thread Gas Double Gas Hose Connector : Amazon.de: Large Appliances