The range of meters on the market varies from simple dwell meters and tachometers to multi-function meters with up to ten different scales and even digital readouts. The meters shown above feature: A Sparktune: dwell, volts, ohms. B Autoranger: dwell, volts, ohms, amps, tachometer. C Testune: dwell, volts, ohms, amps, tachometer. D Hawk: dwell, tachometer. E Avometer 2003: volts, amps, ohms. F CAB-100: battery tester.