There is no faster way to measure and compare peak kV, or verify the proper firing of the secondary ignition system, then with kV/Arc quick probe . Super bright LED strobe allows the user to determine if the secondary ignition is firing consistently, intermittently misfiring, or not firing at all. Indicates spark polarity on DIS systems. Detect problems caused by faulty wires, plugs, cap, rotor coil(s), etc. Works on distributor and DIS systems. Signal receiver probe quickly detects signal. Measures and displays peak spark voltage (kV). Spark Polarity indicators (-green & +red). Battery operated The kv/arc quick probe is easy to use: 1) Simply place the probe over the ignition wire 2) Each time the unit detects a spark firing, it will flash the super bright LED strobe indicating a spark-firing event with sufficient arc duration 3) Then press the button and the unit measures and displays peak kV on the LCD display