The GRT300-NISTL measures earth ground in 4 ranges from 2 to 2000 Ohm. 4-wire, 3-wire, and 2-wire testing. Large dual line LCD. Automatic I (current) and P (potential) spike check. Test Hold function for easy operation. Autoranging, Automatic Zero adjustment, Data Hold and Auto Power off. AC Earth Voltage. Overrange and low battery indication. Complete with test leads with alligator clips, 4 auxiliary earth bars, hard carrying case, and eight 1.5V AA batteries. Includes a limited NIST traceable certificate.