Traditional incandescent lighting illuminates around the perimeter of the dial. Liquid dampened movement provides smooth pointer movement and extended service life in harsh environment applications.. Liquid filled design for superior resistance to shock vibration and the elements.. Autometers Race Proven Mechanical Instruments Provide Trusted Accuracy While Being Simple To Install. No electrical system required for gauge operation - compatible with every street or race vehicle. Gauge kit includes 1/8" nylon line 1/8" NPT compression fittings 1/4" NPT adapter bulb and socket assembly red and green bulb covers mounting hardware and detailed instructions for installation