Simco-ION's FMX-004 Fieldmeter is a compact handheld electrostatic fieldmeter used for locating and measuring static charges. Its pocket size makes it handy to use and four button operation makes it easy to operate.The FMX-004 measures static voltages within ±30 kV (30,000V) at a distance of 1 inch. Results are simultaneously displayed numerically and in bar graph format. POWER on/off, ZERO adjustment, MODE and HOLD are all push button operation. The HOLD button allows the display to retain the static charge reading. This is especially useful where display is difficult to see during measurement.