Midland Metal 700246 Pipe Connector, 1/4 in JIC x 3/8 in Male BSPP, Steel

Adapter, Connection Size 1: 1/4-in, Connection Type 1: JIC, Connection Size 2: 3/8-in, Connection Type 2: Male BSPP, Steel, 7/16-20 x 3/8-19 Thread