Unique three dimensional dial design gives added depth and style to your custom dash. Compatible with most 4 6 and 8 cylinder engines (2 - 4 pulse per revolution ignition signals) with points electronic and most 12V high-performance racing ignitions.. Features metric and imperial scalings for easily relatable readings on applications around the world without the need for mental unit conversions. Modern white LED through-the-dial lighting provides clear visibility during nighttime use. 12 and 16 volt compatible well-suited with nearly every street car or race car electrical system. Autometers Race Proven Air-Core Electric Tachometers Provide Quick And Accurate Readings With A Needle So Responsive It Can Go From 0 - Full Scale In 333 Milliseconds