Mid-West Instrument”s Model 121 indicating differential-pressure switch is a heavy-duty version of the company”s Model 120 unit, featuring a rugged, field-proven piston/housing. The switch also features a heavy-duty, industrial-type terminal strip for either one or two switches. Wired with ½” 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. Available in aluminum or 316 SS pressure housing with 316 SS 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 made of reinforced engineered plastic for corrosion resistance.