This luxuriously soft and supple microfiber is the newest generation in allergen barriers. Air and perspiration porous, Pristine Complete provides a new level of comfort. Easily washable. 25 year guarantee. Microfiber fabrics are new high-tech fabrics made of fibers so thin and yarns so tightly woven that there is no space between the weave of the yarns large enough to allow the passage of allergens. Unlike vinyl encasings, they are truly breathable, that is, both air and water vapor can pass freely through the fabric, even though allergen cannot. They are therefore extremely comfortable, actually imperceptible in use. Microscope photos have shown that many of the competitive products are much less tightly woven than the Pristine Complete fabric. In many cases, the pores in those fabrics are more than large enough to allow the passage of allergens. This is not the case with Pristine Complete - the pores in this fabric are small enough to block common household allergens.