For optimum power and safety, measuring your air/fuel ratio is imperative when tuning. The Grams Wideband Air/Fuel Gauge measures at 52mm (2.047 in.) with an LED display that features a 3 color sweep from red, yellow to green. The Grams Wideband utilizes the latest Bosch(R) 4.9 LSU sensor that displays an easy to read 4 digit display with speedy accuracy down to 0.001.