Are you installing an RNS510 or RCD510 Audio System and do not Bluetooth installed in your vehicle from the factory? If so, you will need to install a 9W7 Bluetooth Module along with this Wiring Harness.
Install is simple. This is essentially a Bridge type Wiring Harness with a Bluetooth Adapter Input. One side of the harness connects to your vehicle's stock Quadralock Harness, while the other side plugs into to your new RCD510 or RNS510 Head Unit. The rectangular adapter with the white swing-lock mechanism plugs directly into your Bluetooth Module.
Also included at no cost is a bluetooth microphone, which is needed to place handsfree calls with your new Head Unit.
Additional coding via VCDS may or may not be required.