Auto Meter 6104 Cobalt Mechanical Boost Gauge Modern blue LED through-the-dial lighting provides clear visibility during nighttime use 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, mounting hardware, and detailed instructions for installation