I have a Humminbird 581 I ( I meaning internal gps antenna) that has been flawless. It's a black & white unit, but color has never been an issuue for me. It does very well with a navionics classic east map card. I also have a Humminbird 798 ci si on the trolling motor for side & down imaging up front where it counts. I really like both of my units & they have performed flawlessly. You can also look in the electronics forum on Bass Boat Central(bbcboards.net) & find some very nice deals on good used electronics.