I have a Helix 7 and I need my Navionics chip to get contours. Also, if you have only the zero lines card, the only contours you will be able to see are the ones you created with Auto Chart. Some of the other Humminbird units have slots for two chip and you can overlay Navionics contours with zero lines auto chart contours. But Helix 7 only takes one chip, or at least mine only has one slot. You can get auto chart to overlay contours on a Navionics card, but your limited to the amount of internal memory on your unit. I carry both Navionics and a zero lines card with me and switch back and forth as needed. Most of the time, Navionics is all I need, as most of the lakes I fish, Navionics is very accurate (lake George). I only use the zero lines on lakes that Navionics is not at all accurate (Saratoga lake) and I have to auto chart to get accurate contours.