Right hopefully i can clear up the doubt in my posts!
Your car will have 1 electrical connection per seat - this is the airbag connection. the connector will be yellow
Note* Early A3's have a different airbag connection than later
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The Seats you plan to fit will have 3 connectors each
Yellow - Air Bags - check your plugs match
Red - Seat Heating (optional)
Green - Electric Adjustment
To fit these seats to your car - you will need a loom from audi to go from the fusebox to the Green plug x2
If the airbag connector is the same - it will just plug in and work fine (once the airbag system is safely isolated)
If you have the red connector - you need a different loom which incorporates Heating and seat electrics as well as dash switches to control the heating x2.
you can buy all the connectors from audi and make your own loom if you know what you are doing, same goes for the airbag plugs.
If this isnt clear - i give up