Pro Air Filter Pre-Oiled Fits Yamaha Yz400 Yz426 Yz450 1998-2009 Pro Air Filter Pre-Oiled Fits Yamaha Yz400 Yz426 Yz450 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Ready to Run, 6 mm outer foam,10 mm inner foam,Bonded dual stage 16 mm filtering thickness,Plush 13 mm sealing foam,Industrial high strength glued seams Provides maximum airflow and increased horsepower,Dual stage open foam matrix,Pre-oiled with Maxima FFT,Complete with disposable gloves, Dyno tested, race proven