Instruments of anti-media and the impact of fluctuating load, vibration-resistant environment, such as outstanding characteristics. Button-meter located on the lower limit of two switch contact device, the pressure to set a signal or when the value of on-off control circuit for the operating system's automatic control or the use. 
General Instrument, contact only applies to copper and copper alloy no corrosive effect of the liquid, gas, media measurement. Button-type contact instruments, also has an outstanding advantage of high temperature acid, is particularly applicable to non-filled liquid, high-voltage (380 VAC, 220VDC) for the user to switch control signals, based on the original contact the head of the increase contacts , The switch to signal more reliable, more stable work, in the case of high-voltage more extended service life, the wider use of machinery, petroleum chemical industry, metallurgy, electric power and other industrial processes.