Voltage control KIT used to adjust voltage from 13.9v to 14.8v (based on 13.9v VR setpoint supplied). The Kit requires the Internal Voltage regulator supplied to be installed "professionally".  It ONLY fits DENSO Design high output alternators (Chrysler Vehicles require units to be sent in). This is a Voltage control knob supplied with a digital voltage meter and Internal Voltage Regulator Comes with: Controller WITH KNOB (not pictured) 8 foot harness with Special Internal Voltage Regulator. Voltage Meter is RED LED and case is Black with Blue LED