XCSOURCE Digital Tach Hour Meter Timer Tachometer Spark Plugs Engine Tachometer Gauge Motorcycle ATV TE101 Suitable for all gasoline engines and be installed above the gasoline engines, with spark plugs Sensor design, just need to tie the cable to the spark plugs and then the item can work One is to be wrapped around a spark plug wire and the other is a ground wire. Low voltage design, powered by built-in batteries (service life: over 3 years), safe and reliable