4K/6K/8K RPM 85mm Marine Tachometer Digital Engine Speed Hourmeter Tachometer Suitable for Diesel Gasoline Vehicles Marine Tachometer 9-32V The sensor needs to be purchased separately. the tachometer does not include the sensor. the sensor does not include the tachometer . please know. thank you! Option 1: 1X RPM Sensor Option 2: 1X Tachometer Package 1 1X RPM Sensor Package 2 1X Tachometer 1X Description Features: x Outstanding Anti-fog function. x Convenient installation through multi-plug socket connection x The protection level is IP67. and the whole is completely waterproof. Specifications: - Name: Tachometer- Red backlight- High precision- Size: 92x50mm- Voltage: 12V/24V- Installation diameter: 85mm- Operating current: 100 MA- Speed ratio: 1-300 adjustable - Function: Current tachometer/RPM and hour - Operating mode: LCD display. stepper motor - Tachometer suitable for car/truck/boat/diesel generator engine/petrol engine Indication range: 0- 8000RPM[85MM diameter]0-3000RPM[85MM diameter]0-4000RPM[85MM diameter]0-6000RPM[85MM diameter] How to adjust the speed ratio 1. Turn on the power first. 2. Press and hold the mode button for three seconds to enter set ratio mode. Then adjust the 1-300 ratio according to your requirements. 3. The data will be automatically saved after setting. 4. If your sensor is installed on the flywheel plate. the speed ratio corresponds to the gear number of the engine if the speed signal comes from the W terminal. the speed ratio is equal to half the number of poles. 5. When the engine is idling. the tachometer normally displays 600-800 U.min. which means the transmission ratio is correct. If not. you can decrease or increase the gear ratio to check the speed difference.