Tests voltage up to 10kV and measures Insulation Resistance to 500GOhm. The MG500-NISTL is a digital high voltage insulation tester that tests voltage up to 10kV and measures insulation resistance to 500GOhm. The MG500 has a CAT III 300 Volt safety rating. This product is complete with a year warranty, built-in heavy duty carrying case with cover, test leads, alligator clips, and 8 x C batteries.