Compatibility: The Marine sending unit is suitable for cars and ships, trucks, buses, boats, etc. Functionality: Output Signal: 240-33 Ohm, Materials: Metal, Length: 100mm / 3.94". Advantage: A durable fuel water-sending unit is intended for a long service life. The fuel sensor is easy to install and use, fix the sensor, then connect the wiring and it will start working. Fuel-sending units for boat tanks are widely used in fuel, water, kerosene, and chemical tanks, generators/generator sets, and marine field. Material: Applying the principle of the magnetic field to control the reed on-off switch, featuring strong corrosion resistance, long using life, anti-vibration, anti-explosion, etc. Installation Steps: How to use fuel gas sender: 1. Just connect a ground blue wire from the marine fuel sending unit to a common grounding hook-up. The blue wire connects to the negative pole of the power supply. 2. And connect the signal red wire from the fuel level sending unit to the gauge hook-up. Package Content: 1 Set Fuel Sending Unit and Gauge. Kindly Know: Please allow 1-2mm error due to manual measurement.