AirNav is the company behind RadarBox24.com, a flight data aggregation service similar to sites like FlightAware.com and FlightRadar24.com. RTL-SDR hardware is typically used to receive ADS-B, and like other providers AirNav have their own custom ADS-B optimized RTL-SDR unit. In addition they sell RTL-SDR's optimized for UAT 978 MHz and the VHF Airband. They also have a range of ADS-B/UAT/VHF airband outdoor antennas as well as filters.
Currently their products are discounted by 20% for Black Friday/Cyber Monday sales. The discount is available on Amazon, as well as directly from their store with coupon GET20.