Auto Meter 4304 Ultra-Lite Mechanical Boost Gauge Traditional incandescent lighting illuminates around the perimeter of the dial Auto Meters 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 Mechanical movements provide accuracy and durability even in the harshest environments 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