The HELIX 9 Sonar GPS is the HELIX 9 series unit which lacks DI and SI, using only 2D sonar. But apart from that, this unit is quite similar to the other units of the series. Therefore, in case you don't want to spend on additional sonar features, but would still like a 9" unit, here's what this HELIX model can do. First of all, the control unit is ready to use as a fish … [Read more...] about Humminbird Fish Finder HELIX 9 Sonar GPS Review