The inner piston is connected to the spring of tightness. When the pressure changes, the spring stretching amount changes correspondingly. When the pressure reaches the set value, it will trigger the preset mechanical structure and send out a switch signal.These compact pressure switches are designed for OEM applications and they are ideal for construction machinery Marine valve remote control systems that require high pressure resistant equipment. The abnormal volume pressure range ratio of 0.3-100 bar (set point optional: piston set point can be more than 200BAR) can be set by factory or adjusted on site.