Midwest Control CTF5050T in-Tank Check Valve, Single 1/8" NPT Tapped Port, 500 psi Max Pressure, 450 Degree F Max Temperature, 1/2" JIC Flare x 1/2" MPT: Amazon.com: Industrial & Scientific
1/8" MNPT x 1/8" MNPT Series 210 Brass Check Valve with Buna-N Seals - 1/3 PSI | U.S. Plastic Corp.
1067: 1/4″ Barb to 1/8″ Male NPT Check Valve | Fittings, Inc.
1/8” 2200 Series Brass Check Valve | Circle Valves 2232-B-1MM | Kleen-Rite
Oldham Chemical Company. B&G Check Valve 1/8 in. NPT
Push to Connect Check Valve Male 1/4" OD - 1/8" NPT Male