Always Use Broan Brand Filters That Are Designed To Work With Your Specific Range Hood. (Ul)(Li)Designed To Fit The 30" Evolution Qp1 Series Range Hood(/Li)(Li)Refer To The Installation Guide Provided With Your Range Hood Or See The Faq Section On This Site For Proper Filter Maintenance And Warranty(/Li)(Li)Sold 1 In A Pack; 2 Required For Replacement(/Li)(/Ul)