Killer B Air Oil Separator Catch Can Add OnThe Killer B Motorsport Performance AOS Catch Can Add On is a component that can be added to the Killer B Motorsport AOS for those that do not want to drain collected liquids back into the crankcase. Features: High Performance Function of our AOS maintained without the need to drain collected liquid back into the crankcase. Made from billet aluminum TIG welded Stainless mount Fitting and Brass Drain Valve Made in the USA