The Humminbird 581i DI Combo combines the power of GPS with Down Imaging technology to give you an edge finding and getting back to the hottest fishing spots. Get a fish eye's view of what's happening below your boat with Down Imaging. Split screen views allow you to see Down Imaging and traditional 2D sonar side by side, for the best understanding of what is under the water. Humminbird exclusive SwitchFire sonar puts you in complete command of how your sonar returns appear. Change display modes on the fly to add or remove detail, account for water depth, temperature and turbulence. Precision GPS combines with Humminbird's UniMap.