HB can use LakeMaster or Navionics mapping ...
LakeMaster has a few more customization options than Navionics ...
To determine your region - Find your lake listing for LakeMaster here ...:
https://www.humminbird.com/support/Find-A-Lake
(Once you open the lake listings pay attention to the legend at the top right that indicates "Bold Hi Definition Survey" means 1ft contours) ...
Rickie