This is a OEM BMW E39 HiFi DSP NOKIA/HAES Professional Subwoofer System. It is used but has been tested and sis in great working condition with almost no cosmetic wear.  

It is a innovative subwoofer box with a single sub built into the enclosure that uses the acoustics of the box to enhance the sound.  It mounts under the rear deck / parcel shelf.  It is great as a low profile sub for any car and sounds awesome too.   We'll cover this with a 30 day warranty (against defect under normal use in the correct application).

Part Numbers: 65.13-6 908 549 or 65.12-8 360 789

List Price: $877.58

Here is a link for compatible BMW Models: 

http://www.realoem.com/bmw/partxref.do?part=65136908549&showus=on&showeur=on&details=1