Fluke 1503 Insulation Tester Live circuit detection prevents insulation test if voltage &gt; 30 V is detected for added user protection Read measurements easily with large, backlit display CAT IV 600 V overvoltage category rating for added user protection Remote probe, test leads, probes and alligator clips included with each tester Accepts optional Fluke TPAK magnetic hanging system to free your hands for other work