ESD static meters and monitor testing equipment locate and measure static electricity and test electronic devices. ESD (electrostatic discharge) static meters measure the static voltages present on an object's surface to determine how much ESD damage can occur to electronic devices. Wrist strap testers are pieces of monitor testing equipment by workers to control and dissipate static electricity. They send a signal from a battery or AC power unit to test the wrist strap's electrical resistance and efficiency. Other testers check the electrical resistance of heel grounders and ESD shoes worn by workers in clean rooms.