CX4A Commercial AIS/VHF AntennaPowerful AIS Tuned commercial VHF Antenna that will give you maximum AIS range. Has a SO239 antenna connector in the base of the Antenna and we recommend using this with low loss 50 ohm coax cable such as RG-213 for best performance (not supplied), particularly on long cable runs.A very high quality 3dB AIS tuned GRP antenna which is ideal for professional and super yacht installation.Specifications:3dB AIS tuned GRP antenna4ft longFit 1.25a ^2 commercial grade fixing bases