The Morehouse 4215 is a robust portable indicator with sensing. What 6 wire meters, such as Model 4215, do is to eliminate the errors from the resistance changes due to temperature, as well as length and gauge of the cable. This indicator can read mVV and use custom (free to download) Morehouse software to convert the mVV units to engineering units with coefficient files from ASTM E74 or ISO 376 reports. This meter is often the choice for accredited calibration service providers wanting high accuracy, convenience and not wanting to break the bank.