Sonar and acoustic systems and equipment, which consist of transmitters, transducers, receivers, amplifiers, housings for the same that may be submersed, mounted, towed, or floated, and operating software, all for communication with underwater vessels; Parts and fittings, namely, transmitters, transducers, receivers, amplifiers, and housings for the same that may be submersed, mounted, towed, or floated, for use with sonar and acoustic systems and equipment; Instructional, training, and teach...