Features: 1.Grooved end makes the contact area between the wire and the instrument large, ensure accurate test. 2.Quality light bulb, high brightness, easy to observe, convenient to use. 3.With portable pen clip, easy to carry and store, bring much convenience for you. 4.Conform to strict quality control standards, dependable to use. 5.Stable characteristics, professional performance, high reliability. Specification: ?Condition: 100% Brand New Item Type: Ignition Test Pen Material: Alloy Color: As picture shown Length: Approx. 125mm/4.9in Diameter: Approx. 10mm/0.4in How to Use: When the engine is started, place the grooved end of the instrument on the spark plug wire. If the bulb flashes, the spark plug wire is transmitting the spark signal. This product can be used to test spark plugs, coils and distributors in two places, the electronic ignition system and the circuit breaker. The grooved end makes the contact area between the wire and the instrument larger, and the high-brightness bulb makes the measurement results easy to observe. Note: Recommended for professional use.