Male Pipe Adapter, Nylon, 3/8" x 1/2", 10 PACK from Cole-Parmer
Gates 3/8, 1/2 Inch Hose Connector/Reducer 28609 | O'Reilly Auto Parts
Vfauosit Brass Pipe Fitting, Water Hose Adapter, 3/8 inch Male x 1/2 inch Female water pipe adapter 3/8 to 1/2 pipe adapter Reducer Adapter 2 Pieces - - Amazon.com