CEN Standard EN 779-2002 rates filtration media. Projects outside the U.S. may use filters with either MERV or CEN ratings. Filters with a class F5 or higher rating are equivalent to a MERV 8 and MERV 10 and filters with a class F7 or higher rating are equivalent to a MERV 13. Additional information on the European Committee for Standardization’s Standard EN 779-2002 can be found on their website: http://www.cen.eu