AutoChart™ for North America (excluding Alaska) takes sonar and GPS recordings from your Humminbird to build custom lake charts. Create your own contour map on any lake in 3 simple steps: (1) Record sonar data after inserting a blank SD card into your Humminbird. (2) Import your recordings into the AutoChart PC program and convert your survey into a lake map. (3) Export your map onto the Zero Lines Map Card (included) to display on any compatible Humminbird.