WIX AIR FILTER - AUDI A4/A5/Q5 WA9638Part No. WA9638 Type AIR FILTER Brand WIX FILTERS Unit of Measure EACH Description WIX AIR FILTER AUDI A4 A5 Q5 Warranty No Warranty Inside Diameter 102mm Outside Diameter 168mm Type Air Filter round Height 167mm Air filters are too often overlooked. Considering as much as 10,000 gallons of air must pass through the air filter for every gallon of fuel the engine consumes, WIX air filters play a vital part in preventing foreign particles like soot,