I have a Striker 4. It's a marvelous fish finder, but Garmin's manual is lame. Mine was virtually useless, until I watched six or so tutorials online, done by One Cast, One Fish. I'm fishing in water that's usually less than three feet deep, so "fish finding"s not my biggest concern. But, that guy at least got me to where I can use it for my needs. It's amazing to me that Garmin built tons of useful things into a small unit, but fails to provide info for us mere mortals to access them. Good luck, IslandJim