Yaesu BU-2 ( Replaced the  BU-1) Bluetooth Adapter Unit.Fits VX-8R, & VX-8DR, FTM-400DR, FTM-350R & FTM-10R Amater Ham Radio tranceivers, & Standard Horizon GX5000S and GX5500S Marine radios Only.Allows use of Optional compatible Yaesu Standard Bluetooth headsets.