Add an antenna to your Mars 300, 400, or 400S system with this Cylindrical Antenna from Hollyland. The antenna plugs into one of the RP-SMA ports on the transmitter or receiver and supports the free 5.1 to 5.8 GHz frequency band. It supports 2 dBi gain and features a standing wave ratio (SWR) of 2.5, maximum. Compatibility: Hollyland Mars 300, 400, or 400S transmitter or receiver