MSD RPM Module Selector # MSD8671MSD RPM Module Selector # MSD8671 RPM Module Selector, Plastic, Black, 4,600 6,800 rpm, 200 rpm Increments, Each Module Selector Range (rpm): 4,600 6,800 Module Selector Increments (rpm): 200 Module Selector Material: Plastic Module Selector Finish: Black Quantity: Sold individually. MSD RPM Module Selectors MSD rpm module selectors plug into the rpm module socket on MSD Soft Touch rev controls, ignition boxes with output for rpm, and any other