Cobra MR F55B Dual-Power VHF Marine Dual-Watch Tranceiver Cobra Dual Power VHF Marine Transceiver with USA, Canada, and International Channels and 10 NOAA Weather Channels One button digital selective calling meets requirements for RTCM-SC101 Digital Selective Calling Weather alert alerts with an audible tone and visual alarm if threatening weather is nearby. GPS capability when connected to a Cobra or most other GPS receivers, you can send your position to other boats in an emergency Dual watch monitors two channels at once - channel 16 and one user selected channel.