DESC: Revolutionary digital music-on-hold playback system supports MP3 and WMA audio formats. The unit has 16mb of on board memory preloaded with over 57 minutes of great sounding licensed music content, so it’s ready to go right out of the box. Add new content to the player by connecting to a PC via the USB port or just slip in a Secure Digital (SD) Card with new content. By adding a SD Card you can increase the memory to 1GB.