Measure voltage with or without test leads Be safer: measure voltage to 600V through the open fork, without test leads Be faster: not need to open covers or remove wire nuts simultaneously measure voltage and current Be everywhere: 17.8 millimeter open fork is widest in the industry; measure up to 200 A on 4/0 wires (120 mm2) FieldSense technology for ac voltage, current and frequency measurement without making electrical contact to live voltage.Jaw Opening:0.7 inch