Install Operation: Wrap the end of the induction wire around the spark plug tube 5 times, then fix it with a cable tie, then insert one end of the induction wire into the groove on the back, find a suitable position and fix the watch with screws. Inductive Digital Hour Meter Waterproof LCD Display for Motorcycle ATV Snowmobile Marine Boat Ski Gas Engine, not tachometer model Features: new and high quality Track the service life of vehicle-oil changes, valve, adjustments, for spark plugs, etc. Easy to install Peel and stick No battery needed - connect to for spark plug wire Works on Any Gas Engine Record and display to 9,999.9 hours Hourglass symbol appears and flashes on/off to indicate counting time Automatic rollover Resolution: 0.1 hour 100% epoxy encapsulated casing resists water, shock, stand the fire of 85C Specification: Item size: 54*36.5*14.5mm Packing content: 1 x Hour meter 1 x Wire 2 x Screw