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Amazon.com: Pressure Switch, Opens On High Pressure, 300 Open (Psi), 300 to 200 Differential Pressure (Psi),210415218 : Industrial & Scientific
Well Pump Pressure Switch - 40-60 PSI Water Well Pressure Switch Electric Auto Control Adjustable Differential 1/4" Female NPT - Amazon.com
Amazon.com: Danfoss Pressure Switch (Range: 1.01 to 2.30 PSI) with Pressure Connection 3/8 G for Air Conditioning System, Heavy Industry, Steam, Liquid, HVAC | Model: RT-112 (Pack of 2) : Industrial & Scientific
Johnson Controls P74EA-8C Differential Pressure Control, SPDT: Electronic Component Switches: Amazon.com: Tools & Home Improvement
Amazon.com: GYL9 AC Residual Current Circuit Breaker Electromagnetic Differential Breaker Safety Switch 4P 40A 63A 100A (Size : 4P 80A, Color : 300mA) : Tools & Home Improvement