Auto Meter 6391 Cobalt Digital Voltmeter Gauge Features Auto Meter's E-Z View Digital LED Display System which maximizes readability and minimizes distracting high speed digit changes Gauge kit includes wiring harness, mounting hardware, and detailed instructions for installation Auto Meters race proven digital stepper motor electric instruments provide unmatched accuracy which is further increased by utilizing a self calibration sequence during power up 12 and 16 volt compatible, compatible with nearly every street car or race car electrical system Registers voltage down to a tenth of a volt