ZRS-AS-21B is part of Carmedia, an automotive entertainment and navigation system. It is a high-end electronic component that enables integrated multimedia access from in-dash sources, such as radio, CD, DVD, USB and Bluetooth. It also supports navigational functions like route-guidance, automatic re-routing and satellite-based position accuracy. Aside from this, the ZRS-AS-21B also supports high-definition digital audio playback, providing crystal-clear sound quality, and includes a Bluetooth audio streaming feature to access music streaming applications.