Mid-West Instrument”s Model 121 indicating differential-pressure switch is a heavy-duty version of the company”s Model 120 design, featuring the same rugged, field-proven piston/housing. In addition, the heavy-duty industrial-type terminal strip can support either one or two switches. Wiring is easy with 1/2″ NPT conduit interface and a removable cover. A variety of switching configurations is available with one or two hermetically sealed switches in SPST, SPDT configuration with 240 volt, 3 Watt or 60 Watt ratings. The switch is available in aluminum or 316 S.S. pressure housing with 316 S.S. and ceramic internal parts. Safe Working Pressure is 6000 PSIG (0-400 bar). Differential pressure ranges from 0-5 PSID (0-.3 bar) to 0-110 PSID (0-7 bar) with +/-2 percent accuracy. The weather-resistant gauge front is reinforced engineered plastic for corrosion resistance.