This module allows you to recalibrate OEM electronic speedometers when changing tire size, pulley, or final gearing. Easy installation – simply plugs in between the pickup sensor and the stock wiring harness. Allows small step corrections of less than 1 mph. Correction range of 50% to 200%. No power required to maintain calibration when the bike is parked. Two sealed buttons allow easy resetting of the speedometer reading while the bike is in motion. A must for custom builders using electronic speedometers.