The mountune high flow air filter for the Mk3 Focus RS has been designed for maximum air flow and efficiency while maintaining superior filtration and features propriety double-layer cotton gauze with deep pleats that creates a 10-15% increase in filtration surface area compared to other filters on the market. The oiled filter media is incapsulated in steel mesh that helps to maintain the perfect shape under the most extreme conditions. Each mountune high flow air filter is manufactured using a four step process resulting in a precision fit and virtually no seepage of rubber frame material into the filter media producing the maximum available filter area. Additionally, the mountune high flow air filter features a factory style locating outer flange that helps lock the filter in place to ensure correct pressure on the inlet flange. Features: OE-quality fit Increased performance Increased induction noise Pre-oiled Lifetime warranty Please note: A K&N equivalent filter may also be supplied.