Look up Youtube videos on the Garmin livescope. Many are using more than one sonar. The GPS store has all the models at a good price. Call them and talk to them. They have a website.

I just want to say that the livescope is a good tool to help you. I knew EVERYTHING about crappie before I bought it. It does not help you find them if you don't know where to look. Anyone that buys one is simply upping their game to catch more when they go out. It does help you see where the crappie are so you catch some big slabs!