Checking the spark in relation to the piston ensures that your engine is firing as efficiently as possible. The Tac-Style Shift Light from PROFORM allows you to check timing, help diagnose a no-spark condition and check for electronic advance/retard! Use with 2, 4, 6- and 8-cylinder applications. Featuring 1-wire inductive lead design and a high-intensity LED that's visible in sunny conditions, which makes using this tool simple and easy to use. Running on a Li-ion rechargeable battery, via mini-USB cable which is included, this light can also be used as an all-purpose flashlight for use at home, car, or in the garage. The sleek machined aluminum body has a tactical inspired design that fits comfortably in hand for prolonged use. The head of the light features an O-ring sealed tempered glass lens, designed for a tighter light beam to better aim at the timing mark. Weighing in at just under 1 lbs., with a black anodized finish, this light has a sturdy construction that can stand up to the rigors of heavy use.