Simpson’s high precision Model 444-2 has been redesigned for added ESD immunity and longer battery life. The model 444-2 Micro-Ohmmeter measures resistance from 50 micro-ohms to 20 ohms. It measures using an extremely small test voltage (100 microvolts maximum) and a four-wire measurement technique. The resistance reading is indicated on a 4-1/2 digit LCD display using one of two measuring modes: An automatic AC measurement mode or a manual DC measurement mode. By limiting the test voltage of the Model 444-2 to only 100 microvolts the instrument will not "punch through" contamination or corrosion. An audible tone can be used to indicate resistance values below any selected reading. The Model 444-2 has a universal power input range of 85Vac to 250Vac and incorporates a self-contained rechargeable Ni-Cad battery for field use.