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 and 4 Stroke Tachometer measures engine speed up to 9,000 RPM. Detachable and replaceable cable set Professional timing light with very bright LED digital display of RPM and Advance. Pushbuttons on the control panel change themode, increase/decrease advance degrees and switch between 4 and 2 cycle. Designed for precise tuning and diagnostic work. Unit is accurate to 9,000 RPM and works with 12 Volt systems.