The Extech MG300 is a True RMS multimeter with built-in insulation resistance tester with the added safety of wireless data streaming for remote monitoring and data logging. By adding insulation testing capabilities to the ubiquitous digital multimeter, electricians are always equipped for insulation testing, helping make it a more routine part of predictive maintenance with faster troubleshooting and repairs without additional tools. The rugged and waterproof (IP67-rated) combination meter includes a digital insulation resistance tester (or megohmmeter) with 4 different test voltages for measuring resistance up to 4GΩ with 0.001MΩ resolution.