These are removable micro SD cards and SD card adapters that contain fishing hotspots. Each fishfinder comes with micro SD or full size SD card slot to install waypoints, retrieve screenshots, update software, or install upgraded contour maps.
These SD cards are mainly filled with fishing hotspots and creek channels to help you narrow down where the fish are quicker to help you run a pattern of how to catch fish all over the lake.
These are designed to give the newer anglers, weekend warriors, or traveling tournament fisherman the best odds at doing well when they can't spend all of their time idling around and looking for structure. Take the hard work of guides to be able to narrow down where high percentage spots and populations of fish are to make your days on the water more enjoyable.