There's no need to worry about unseen dust mites with our superior quality barrier covers.  Made of 100% organic cotton, the fabric is woven so that no opening is larger than 6 microns in size to prevent dust mite and pet dander migration.  It's breathable too, with a soft 400 thread count. The zippered closure is made of PVC free plastic with tight teeth, unlike brass zippers, to ensure your safety.   No chemicals, dyes or bleach are used. SKAL certified AND dust mite tested by an independent lab for your peace of mind.