All Garmin units have a factory loaded basemap and basically most any basemap will work with this map. Depending on the unit that could be one of several types, but it will always be named gmapbmap.img. There may be a version available later than your current basemap. Again depending on the unit it may be found in either the unit's Garmin or .System folder, or in very old units in an inaccessible flash region and therefore unable to be changed by the user. Modern automotive units have a routable all-world DEM basemap, older ones have a non-DEM regional basemap which includes only very basic data for the rest of the world e.g. Atlantic, Americas & Pacific all have 'WORLD MPC' as well. Dedicated Outdoor, Marine and Aviation units have specialised basemaps preloaded. See [Only registered and activated users can see links. ] - scroll down to 'World and Base Maps' if you want to update your basemap.