I contacted humminbird today. They told me I could use either the hotmap or hotmap preimium.They also gave me the # of navionics and I called them. They also said I could use either the navionic hot map or hot map premium. I told them i needed a map of truman lake as I am going there in the end of april. They said the map on either chip was the same and if that is all I needed The lower priced hot map would be sufficent for thr humminbird.