Humminbird AutoChart Zero Lines Map Card - High-Depth Fishing GPS Chart for LakeMaster & AutoChart Live - Perfect for Freshwater & Saltwater Fishing

I've used it for a while. Some folks say you don't need it on lakes with Navionics coverage, etc. But in reality these are decades old hydrographic maps, most have changed considerably over the years, and even then they aren't that accurate. So the ability to create your own, recent, accurate, map is a great feature.The ZeroLines map card works fine (allows you to store your charts and view them on your sonar unit), but the AutoChart/Pro computer program itself is a bit weak. The interface for creating maps is awkward in some ways, although is functional in the end. I think the main problem is the user manual isn't very helpful. It isn't written from the perspective of a new user, so you are mostly left to figure things out on your own. Once you do it's OK, but the manual could be a lot more helpful.