Gas meters, equipment and instruments related to the metering and utility industries, namely, meters for natural gas, hydrocarbons or air, positive displacement rotary meters, standard modules that measure uncorrected volume of natural gas, hydrocarbons or air, test and calibration equipment for testing and calibrating the functionality and accuracy of meters and modules; auxiliary products related to the metering and utility industries, namely, master meters, test meters, back-up counters, internal pulser, external pulser, pressure plugs, filters to protect against debris from entering the meter, tach-adapter; equipment and instruments related to the metering and utility industries, namely, electronic volume correctors, electronic and mechanical modules that measure gas, hydrocarbons or air and correct for temperature, temperature and pressure, temperature, pressure and gas compressibility, communication module that generates cyclical pulse output or audit-trail, remote and meter-mounted volume correctors with the capacity to communicate cyclical pulse output and audit-trail, test and calibration equipment for testing and calibrating the functionality and accuracy of electronic volume correctors, communication module that generates cyclical pulse output and audit-trail