AEV's ProCal Module is a hand-held powerhouse! This essential tool provides JK owners an easy, low-cost way to make a variety of useful changes not offered by the dealer or any other re-programmer. Topping the list is the ability to correct the speedometer and gear ratio when larger tires are installed. With the speedometer left uncorrected, there is a major degradation in the performance of the stability control (ESP), transmission shifting, and engine performance. The best part of the ProCal is that it isn’t just for correcting the speedometer. The Tire Pressure Monitoring System can now be recalibrated to better suit aftermarket tires without triggering the dash light. Further, the ProCal Module makes it possible to activate daytime running lamps, "one-touch" turn signals, enable a temporarily increased engine idle speed for winching, clear engine codes, and even has a feature to help align the vehicle perfectly for optimal ESP performance.