Any change in a vehicle's tire size or rear axle ratio will cause the speedometer (and odometer) reading to be inaccurate. The Electronic Ratio Adapter (ERA) is designed to correct this problem. It receives the current speedometer signal from the vehicle speed sensor and sends the correct speed signal to the speedometer. The ERA installation is
a snap with only four wires (input, output, hot, ground). Set the dip switches following the Abbott Calibration Table and your ready to go. The ERA has one of the widest pulse ranges available.