Auto Meter 3966 Sport-Comp Playback Tachometer Traditional incandescent lighting illuminates the front of the dial 12 and 16 volt compatible, well-suited with nearly every street car or race car electrical system Auto Meters 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 Compatible with 0.5 - 6 pulse ignition signals (1-12 cylinder engines) with points, electronic, and most 12V high-performance racing ignitions. Record up to 80 seconds of engine RPM data and playback at slow motion speeds to analyze vehicle and driver performance following a run. Identify key performance data such as burnout, launch RPM, tire spin, gear changes and engine speed through the traps to fine tune your setup and trip the win lights.