Stack Professional GPS Speedometers utilize the latest satellite signal technology to simplify instrument installation and accurately register vehicle speed. The included high - speed (10 Hz) omnidirectional micro antenna offers exceptional mounting versatility and eliminates the need for recalibrations associated with conventional speedometers when making adjustments to vehicle gearing or wheel circumference. Inboard configurable LED digital display indicates odometer, trip odometer, timedate, position coordinates, heading data, compass, peak speed recall, and performance meter acceleration and braking tests.