O-ring for the original blow off valve for all 2.0L and 1.8L TFSI / TSI engines. The divert-air valve is very susceptible and often leaks. The O-ring should be replaced with every installation. Manufacturer Information about the manufacturer BAR-TEK BAR-TEK Motorsport GmbH Im Rauschen Auel 3, 51491 Overath-Brombach, Germany info@bar-tek.com