The TUA-T550HD HD Radio tuner is a small hide-away box that can be connected to any of Alpine's 2008 model Ai-NET head units to add HD Radio Technology as a source. With HD Radio receivers, consumers gain crystal clear music and talk from the more than 1,500 AM/FM radio stations nationwide that are currently broadcasting digitally. When the head unit is tuned to an HD Radio station, the head unit's display will list artist, album and song information, if this selected station chooses to broadcast this metadata. As an Ai-NET pass-through source, the TUA-T550HD also allows for the addition of other Alpine Ai-NET audio sources, such as satellite radio, USB-based MP3 players and Bluetooth.Users may also enjoy HD Radio broadcasting's unique multicasting benefits. FM multicasting allows consumers to listen to HD2 and HD3 multicast channels above and beyond the main station. This allows stations to expand their offerings to the public, without the fees associated with satellite radio.