The Major Megger® insulation and continuity testers MJ10 and BM12 are modern, portable, self-contained instruments designed to give rapid and accurate measurements. They have four d.c. insulation testing voltages 100 V, 250 V, 500 V and 1000 V, and a single insulation resistance range of up to 2000 MΩ. Similarly, continuity is measured, with either polarity, on a single 0-4 Ω range.