Filter Minder ® Graduated Switch Indicator Model No. 135578 (1/8" pipe thread) 136578 (3/8" straight thread) 137578 (M-10 thread) How Does It Work? A combination graduated indicator and switch, the position indicator progressively fills the window as air filter restriction increases, locking at the highest restriction. When it reaches the red zone, or highest recommended restriction, it sends a signal to the filter warning light on the dash or to the engine computer to record as a diagnostics fault. The warning light locks on until the indicator is reset. Specifications Operating Temperature: -40 to +250°F (-40 to +121°C) Switch Activation Point: 8" water vacuum (2kPa) minimum to 35" water vacuum (8.7kPa) maximum. Contact the company for special calibrations. Accuracy: ±10% at switch activation Material: Polycarbonate housing Normally open or closed switches with precious metal contacts Molded in sealed connector Dimensions Length: 78.9 mm Diameter: 50.9 mm (with connector: 64 mm) Engineered Products Co. 2940 Airport Blvd. Waterloo, IA 50703 Ph: (319) 234-0231 Fax: (319) 234-8922 info@filterminder.com