Simple, high quality tool designed to test high energy electronic ignition (HEI) systems. Simply attach plug wire to end then use built in clip to attach to ground. Tester will give you true spark performance results, helping you identify ignition anomalies that simply removing a plug and grounding it won't reveal. For use on vehicles and power equipment equipped with a high energy ignition system. Value is at the core of the OTC tool and equipment portfolio. Whether it's a simple repair or the most complex drivability concern, these award-winning tools universally solve problems faster, and at better value, than any other product line available. Whether it's a specialty tool or unique piece of service equipment, OTC provides top solutions to modern automotive service challenges while increasing technicians' productivity and shop profits.