The GRT300 measures earth ground in four ranges, from 2 to 2000 Ohms. Testing can be done using four, three, or two wires. Large dual-line LCD. Automatic I (current) and P (potential) spike detection. The Test Hold function allows for easy operation. Autorange, Automatic Zero Adjustment, Data Hold, and Auto Power Off. AC Earth Voltage. Overrange and low battery indications. Includes test leads with alligator clips, four auxiliary earth bars, a sturdy carrying box, and eight 1.5V AA batteries.