An easy to install inductive tacho and hour meter for petrol engines to help indicate when you should maintain your engine to avoid downtime and costly rebuilds. It is completely waterproof and dustproof with IP68 rating making it ideal for boats, trucks, compressors or any harsh environment. When the engine is running, the LCD unit reads revolutions up to 60,000 RPM with accuracy of 10 RPM; switches to hour meter when the engine is off. To install simply connect the 1.6m long lead to ground and around a spark plug lead. No battery required - charges from the spark plug wire User adjustable spark setting from 1 spark to 8 sparks per revolution Max RPM reading Max reading: 60,000RPM and 99,999 hours Dimensions: 71(W) x 41(H)mm