Traditional incandescent lighting illuminates around the perimeter of the dial. The included Type K thermocouple assures maximum accuracy and minimum response time. Autometers Race Proven Digital Stepper Motor Electric Instruments Provide Unmatched Accuracy Which Is Further Increased By Utilizing A Self Calibration Sequence During Power Up. Gauge kit includes Type-K Thermocouple wiring harness extension module various methods for thermocouple installation bulb and socket assembly red and green bulb covers mounting hardware and detailed instructions for installation. Features front sealed bezel design for added water resistance and UV protected paint on dial pointer for added protection against sun damage. 12 and 16 volt compatible well-suited with nearly every marine electrical system