Calibrating A Speedometer Isnt A Great Deal Of Fun, But Stacks Electronic Programmable Speedometer Makes Short Work Of The Process, Providing An Easy To Install And Easy To Calibrate Solution That Will Help Keep Your Speed Exactly Where It Needs To Be. Compatible With Most Factory And Many Aftermarket Speed Sensors, You Will Wonder Why You Ever Struggled With A Speedometer Before. Calibration Is As Simple As A Two Mile (Or Kilometer) Drive.