Raymarine Wireless Mast Rotation Transmitter antennas am fm antennas Attach your radio securely and Select::OCEAN Solid Fender BLADE, Navy Blue 197746 Attach your radio securely and quickly for hands free use in any environment 1x Frame for wall mounting Operating as a wireless device on a Micronet network the Mast Rotation Transmitter compares compass information from the boat with its own information and corrects the wind angle coming from a standard wind transmitter at the mast head Easily installed at any convenient position on the mast the Mast Rotation Transmitter can be calibrated simply from any Digital or Dual Digital Display in the system