em-trak B921 Class B AIS Transceiver - 2W CSTDMA [430-0001]B921 Class B AIS Transceiver 2W CSTDMA **As the FCC requires all units sold in the US to be programmed by a qualified technician. Please submit the form below for programming at the time of purchase. A copy of the MMSI registration or FCC Ship Station License is required along with the vessel master or owner's signature on the completed programming form.** Click here to download form. The B921 is a 2W CSTDMA Class B AIS transceiver, delivering em