The Fluke 175 ESFP True RMS Digital Multimeter -is compact, rugged, reliable, and easy to use. Unlike averaging meters, which can accurately measure only pure sinewaves, true RMS meters accurately measure distorted waveforms. Calculating true RMS converters require a certain level of input voltage to make a measurement. The ac voltage and current ranges are specified from 5-Percent of range to 100-Percent of range.