I bought a used Northstar 951X and it had a chart card in it. I don't see any reference to the number on the Navionics web site. Maybe it is to old. Code US056D08 Lake michigan East, dated July 1995. In pen someone wrote WGS84. It does work but that is all I know. Is it still usefull for that area that someone would want to buy it or is it junk? Since I am in California, doesn't do me any good. I need a US644XL instead.