JDM stands for Japanese Dual Movement. These gauges combine state-of-the-art features with terrific readability. Each gauge has both an analog needle AND a digital display on the same gauge! Plus, tracer LEDs around the perimeter of the gauge track the movement of the pointer needle -- and turn red when the gauge has reached its pre-set warning point.
Note that these are 60mm gauges. Each gauge comes with 60mm gauge cup for stand-alone mounting.