If you have a new model GM, Ford, Dodge or Jeep truck or SUV, then the JET Performance Accu-Speed Speedometer Calibrator is an excellent option for you. This exceptional speedometer calibrator communicates with the speed sensor of your vehicle. The JET Performance Accu-Speed Speedometer Calibrator can be attached to the transmission output speed sensor. If you have a vehicle and you have made smaller or larger tire diameter modifications, this unparalleled speedometer calibrator will enable shift point alteration and speedometer calibration. The JET Performance Accu-Speed Speedometer Calibrator is able to fix the speedometer after making gear ratio or tire size adjustments. JET?s engineers have created the Accu-Speed Speedometer Calibrator to alter speed sensor output readings. The calibration is simple ? you only have to turn a switch. You can install your new JET Performance Accu-Speed Speedometer Calibrator instantly and with no difficulties. But, please, keep in mind that the installed product cannot be returned.