SonarPhone by Vexilar!

As the name implies, SonarPhone turns your smartphone or tablet into a fully functional touch screen sonar system that will rival the performance of sonar systems costing hundreds more. You dont need cell phone coverage to use it, the SonarPhone Sonar Transmitter will work anywhere in the world. (#SP300 only)> Carry case with 12 volt battery and charger: (#SP300 only)