In conjunction with the USCG Automatic Identification System (AIS) requirements for commercial vessels, Digital Antenna created a series of 4 AIS antennas that meet the exacting AIS frequency requirements. Designed with a low 1.5: 1.0 SWR ratio from 159-162 MHz, Digital Antenna's 4.5 dB gain AIS antennas offer unsurpassed durability and performance that's compatible with all AIS transponders. All antennas are made in the USA, assembled, tested, and tuned by hand for maximum performance. Marine-grade, fiberglass construction ensures years of use. Each antenna comes with stainless steel double female ferrule for mounting a 114-thread base. Cable not included. Features:• Powerful brass radiators• Soldered connections• Power directing ferrite choke bead• High-gloss urethane finish• 316 stainless steel ferrule• 4.5dB gain Marine-grade, fiberglass construction Hand-tuned for maximum performance | Digital Antenna 876-SW 4' AIS Antenna Made in USA