Traditional incandescent lighting illuminates around the perimeter of the dial. Gauge kit includes 1/8in NPT temperature sender 3/8in and 1/2in NPT adapters wiring harness bulb and socket assembly red and green bulb covers mounting hardware and detailed instructions for installation. Includes data acquisition grade temperature sender providing unmatched accuracy and durability even in the harshest environments. 12 and 16 volt compatible compatible with nearly every street car or race car electrical system