Hey , I have a Garmin and a Lowrance chart plotter. The garmin can only use garmin charts . I put a navionics chip in the lowrance and the detail in the bay and rivers is great. The lowrance lake maps cover most of the lakes in the U.S. and you can make your own maps with the lowrance. I have a lot of $ in the garmin so I will keep it till it dies And Lowrance/eagle has the best sounder on the market hands down.