The TENTECH MD542 is a smart, microprocessor controlled, 500 V insulation tester for up to 100 GΩ @ 500 V resistance measuring with 100 V, 250 V and 500 V test voltage. It is a portable, handheld, battery-powered equipment. Due to its measurement principle (actual voltage and current readings) it is a "true megohmmeter" and so the accuracy of resistance measurement is not affected by any test voltage error.