For over thirty years, Quorum Pharmaceuticals has worked closely with doctors to develop effective allergy products and services. Using the professional medical advice of these allergists, Quorum Pharmaceuticals developed the Zip & Block range of zippered mattress, box spring, pillow and duvet encasings. As recommended by allergists, they are unquilted and manufactured with an interior zipper flap and reinforced inner seams for the most effective barrier to dust mites and related allergens.