The Sensor of the Switches is capillary thermometer bulb,can be apply to gas which will not exert corrosion on Brass and Brass alloy , steam such gasous medium or liquid medium. The Set Point Adjustable range is from -60℃ to +170℃.  WTZK-50-C ,the shell material is Casting Aluminum, water-proof structure can meet the requirements of vessel use. WTZK-50 ,the shell is phenolic plastic, it is the general type.