These unique pillowcase and mattress covers are soft, breathable and comfortable bedding products, which provide effective protection against asthma causing dust and dust mites. All Miteclean products are made of very tightly woven lint-free yarn with a pore size less than 8.5 microns. This prevents dust mites and their droppings from reaching your face during sleep. This fabric has special Dupont Negastat yarn added which prevents any surface voltage.