2 The American muscle gauges from Auto Meter are pretty much the coolest instruments this author has seen in a while. The brushed stainless face combined with the bright orange needles and black numbered area just looks mean, but still refined. All the gauges in this line are electric so the needed sensors are provided except the speed sensor. The speedometer and tachometer measure 3-3/8-inch diameters while the other gauges are 2-1/16-inch in size. We also added the LED lighting dimmer so we can adjust the brightness of the new LED gauges.