This RPM shift light is a stand alone adjustable knob model so no chips or external modules are needed. Unit has a 3,000 to 12,000 RPM range and reads in 200 rpm increments. Shift light has a 1.5 inch overall diameter, 5 inches long and is 2.75 inches tall. Compatible with 4-6-8 cylinder engines. Features a black finish aluminum body and includes a yellow light cover. Some applications may need a late-model tach adapter. Sold individually. Backed by a limited 30 day factory warranty. Sold individually.