The em-trak B400 is a high-performance Class B AIS (Automatic Identification System) transceiver designed for commercial vessels, workboats, yachts, and leisure craft. It uses SOTDMA technology and a 5 W AIS transmitter, providing improved reporting performance and signal priority compared with standard 2 W Class B AIS units.

The B400 features a 5-inch full-colour display, integrated AIS target monitoring, collision alerts, CPA functions, vessel lists, AIS messaging, and ENC chart display capability. It also supports GPS/GNSS positioning, Wi-Fi, NMEA 0183, and NMEA 2000, allowing integration with chartplotters, ECDIS, and other bridge navigation equipment.