BMW e46 (2-door) Alternator cooling Air Duct Lower NEW generator cooler wind guide Alternator Air Duct Lower NOTE: for COUPES (2 door) and Convertibles ONLY. BMW part# 12 31 1 712 932, check fit below. Genuine BMW part, recently made: not been lying around. Please see FITMENT CHART below, under PRODUCT DESCRIPTION. Email us your VIN for any questions.