ShakespeareÃ‚Â·OutdoorÃ‚Â·VHFÃ‚Â·MarineÃ‚Â·3 dBi gainÃ‚Â·omnidirectional 396-1-Ais is a center-fed 1/2 wave coaxial sleeve VHF marine antenna with a total length of 4'(1.2 m). It is specially designed for use with AIS equipment and meets the strict requirements of the AIS specification. This single-segment antenna has an aluminum sleeve for mast installation.