Pristine® is one of the best know allergen barrier fabrics on the market. It is a patented, membrane free, micro-weave polyester fabric that feels nice to the touch and has a small 5.7 micron pore size to offer great protection against dust mites and their allergens. It provides a cool, quiet and breathable sleeping surface that is unnoticeable under your bedding. These dust mite covers are very durable and retain their tight weave longer than most top quality, woven allergen barrier fabrics. Pristine® dust mite covers are a good choice if you like to (or need to) wash all of your bedding often. Please note that these comforter covers will have a seam in them as the Pristine® fabric is only made 66-inches wide. We recommend using a duvet cover over the comforter cover and visually this will not be an issue; however, it is worth noting for those who are picky about seams.