I have both, and the mobile app shows 1' contours and when I was viewing the same lake with the Hotmaps premium chip in my Humminbird Helix the chart only showed 5' contours. What's up with that??? Funny how before I was happy with a paper map but now since I paid for the technology I want more! Anybody have any experience with the Hotmaps Premium? Thanks. BTW I was viewing Big Sand Lake in Vilas County.