Handheld Megohmmeter1 MΩ TO 200 MΩ500V, 3.5 DigitThe Model R1M-B Handheld Voltmeter/ Megohmmeter is designed to measure insulation resistance in live circuits, which may have voltage present. It can be connected to 600 V RMS AC or DC without damage, and its mode of operation is automatic. It has no fuse to replace. The R1M-B will operate after a drop from a height of four feet to a concrete floor. All units are tested in an environmental chamber at 71° C and 95.5% RH.The R1M-B complies with MIL-PRF-28800, Type III, Class 3, Style E for rugged operational environments and shipboard applications. These units perform under the extremes of heat, cold, humidity, shock, vibration, and operator abuse.