If you are buying a fish finder, here is a question to ask yourself and a tip to give you an idea of the fishfinder that will best fit your fishing situation. 1. Are you in the ocean off shore, or are you on a small lake or river? If you are fishing in the ocean off shore, out of site of land, there are a few things you'll want with your fishfinder. GPS to identify where you are and how to get home. A good saltwater capable transducer capable of cutting through the salt water to good depths. If you are in a small lake or river, you dont necessarily need GPS, unless you want to plot waypoints to specific fishing hole locations to within 3 meters. This can be very helpful however. 2. Get a good dual frequency transducer. A dual frequency ducer gives you the ability to swicth between the 50 khz wide beam cone and the narrow 200 khz narrow beam cone. The wide beam cone returns a larger section of the floor beneath the boat, but will not penetrate the water as deep and the return image is at a lower resolution. The narrow beam cone, returns a smaller section of the bottom, but can penetrate the water to a greater depth and returns a more highly detailed scan. When you scan at the lower frequency, you can cover more ares, then switch to the narrow, high detail beam to get a clearer picture of what has caught your eye.