I have a garmin 550 on the front of boat shows fish and stucture good. But I heard so much about Humminbirds di I bought a 581di for gps and di. Unit is not color like garmin dont really like it that well. Took garmin off front put 581 bird there had terrible trolling motor interferance, took bird off put it on driver console put garmin back on front. At least I can use 581 for gps, mark brush, and down imaging. Any body else use garmins, I really like mine. And anybody like there 581di mono chrome.