The INNOVA 3551 Inductive Timing Light Check is designed to accurately read timing, diagnose a no-spark condition, check for electronic advance/retard and more. This includes slim, rotating barrel for better aim at timing mark and protective hand guard for one-hand operation. Works with most ignition systems: DIS, conventional, electronic, and computer-controlled systems - domestic and imports. The INNOVA 3551 also has the Patented Skip Circuitry Test up to 9,990 RPM.