These unbleached, chemical-free 100% natural cotton covers offer supreme bedtime comfort. These zipped wholly natural allergen barrier covers offer total enclosure. The specially woven cotton, tested by the BTTG laboratories in Manchester and the Medical Entomology Centre at the University of Cambridge, is impenetrable by microscopic house dust mites and more importantly by their even tinier allergen-containing droppings. They come with the Eco-tex guarantee of textile purity and are highly recommended for skin problems and dust mite allergies.