Professional Timing Light with High Visibility LED display Very bright display indicates: - Tach (RPM) - Degrees Advance; Measures ignition spark advance from 0-90 degrees; 2 & 4 Stroke Tachometer measures engine speed up to 9,999 RPM; Brilliant Xenon flash at all speeds; Detachable & replaceable cable set; Designed for precise tuning and diagnostic work; Accurate up to 9,000 RPM; Works with 12 Volt electrical systems