I use the Lowrance Mark 4 HDI both on my boat and on the ice for the first time this season. I put a lot of hours on it in the LI Sound this past summer and fall and couldn't have asked for a better unit. The map, downscan, and sonar work awesome. I got the ice pack for it too which comes with a bag, mount, battery and ice ducer. Despite the small screen size it works great as a flasher. I payed $175 for the unit and $120 for the ice pack. No complaints here, highly recommend it.