The ContourXD maps are the new base maps that will be in some of the 2010 Humminbird units (not sure about the 300 and 500 series units). Some of these lakes have depth contour lines on them. Don’t expect the same number or definition as the HD lakes off the Premium and Platinum map cards from Navionics though as I’ve heard some have 10 foot contour lines while others have 20 foot contour lines. These cannot be loaded into existing units and have to come from the factory with them already loaded.