The fuel level gauge works by delivering a low amperage current through the gauge's meter to the ground via a variable resistance transmitting device. As the tank empties, the float falls, and a movable contact moves along the resistor, increasing its resistance. Furthermore, when the resistance reaches a specific level, it will illuminate a "low fuel" indicator on select automobiles. The indicator unit measures and displays the electrical current passing through the transmitting unit. When the tank level is high and has maximum current, the needle will point to "F," indicating that the tank is full. When the tank is empty, the least amount of electricity is flowing, the needle points to "E," which shows that the tank is empty. Key Features: Glass lens with anti-scratch coating 12 volts direct current negative ground It is adaptable to 24 VDC systems. The equipment has a white dial with striking Black designs on the rim. Bezel in black aluminum White pointer with a curved tip and a flat glass lens Specifications: Brand: Faria SKU: F12901 Weight: 0.26 lbs UPC: 759266129016 Gauge Type: Fuel Level Series: Euro White Voltage - Input Range (Volts): 12/24 V Gauge Size: 2" Condition: New Product alternative SKU: F12801, F16001