I need to replace the slider vents to the AC center front need to know a part number and description to order

LOOK ON YOUR WINDSREEN ,get the last 7 digits of the vin/chassis no (usually 2 letters and 5 numbers) ring BMW and they will tell you exactly which part you need and what your part number should be. simple!

As your car is the age it is i expect at some time in its life the windscreen has been replaced and most liokely not a bmw window, so the number will be coverd up so u will have no info on it and most will genuine windows have carpark tickets that have slid behind the dash covering up the chassis no. I would just look under the bonnet for the plate and quote the number, a lot of dealers these days go on reg numbers anyway and their system will bring all your car details up, just ask what part u r after.