I have 2 on my big boat a garmin and a lorance, the lorance has a chip with contours I use it more. My 17 foot boat has a hummingbird helix 5 with a chip it also works very good. But I also have the avitonic app. On a iPad with a bad elf receiver that I use on both boats and in my RZR. I like it the best. The contours are more accurate. The app is 10 bucks and the bad elf GPS receiver is 149 bucks. They are all pretty good depends on how much you want to see. That’s my 2 cents. Sent from my iPhone using Lake Ontario United