The HELIX 5 CHIRP SI GPS G2 is one of the newest models from Humminbird for 2017. It comes with quite a few improvements over the older HELIX 5 SI GPS. The major differences are the CHIRP sonar technology and the AutoChart Live capability. As its name suggests, it's a unit with GPS and Side Imaging sonar, but it also has Down Imaging and DualBeam Plus standard sonar, all CHIRP enhanced. As for base maps for navigation, it comes with the Humminbird UniMap charts.