Obviously by the response, not many of us! You must be writing about the brands that transmit a signal from a bobber casted to an area where fish might congregate. I'm not impressed with the outcome or the out lay. Cheep or good, once the transmitter is cast, it's looking down. A car topper boat or raft might be a better way to go. Sonar is nice to have when hunting for underwater structure. May I suggest looking into under water TV ? I use both...From a boat. The new technology for underwater HDTV is unbelievable!