The C406 series Emergency Locator Transmitteris an automatic fixed type ELT which transmits on 121.5, 243.0, and 406 MHz frequencies. In the event of a crash the ELT automatically activates transmitting the standard swept tone on 121.5 and 243.0 MHz.It also transmits a 406 MHz encoded digital message to the Cospas/Sarsat satellite system, which allows for rapid identification and reduces Search and Rescue response time.ModelC406-NHM is a single BNC output ELT with a multi-axis G-switch for helicopter applications. Connects directly to aircraft navigation. Capable of custom programming wisth optional adapter.