Stack offers mechanical gauges with reliability and performance specifically designed for vehicles with no or low-powered electrical systems. These mechanical auxiliary instruments feature quick-read full sweep movement, white or orange LED-illuminated needles to ensure excellent readability day or night, and they require no power for operation. These gauges are perfect for enthusiasts on a budget! For compact, rugged quality with simple, easy-to-read data at a competitive price, choose Stack mechanical gauges. These are the most accurate mechanical boost gauges we have tested!