Steel 1/4'' NPT Inline Air Regulator Air Pressure Valve Control Tool 3pcs | eBay
Inline Pressure Regulator with 1/4 in. Press-in Tube Fittings - AndyMark, Inc
MEANLIN MEASURE 1/4 Inch Air Compressor Regulator with Gauge, 0-180 PSI Air Gauge Regulator Inline for Air Compressor and Pneumatic Tools (Four-way valve) - Amazon.com