All the Birds have the dual 19/9 degree ducers, I have had the Ice 35 & Ice 45, the Ice 45 is awsome.
If I had the extra $100, I would get the Ice 55. With the Ice 55 you get the 6 colors, a soft pack, the target line & the extra power over the Ice 45.
As another guy said check out their website, they have a video that shows the diffrences.
I really wish I would have spent the extra $100 for the Ice 55 now.