These mattress encasements are impenetrable to bed bugs, preventing bed bug bites while you sleep. Tests conducted by an independent entomology laboratory showed that the encasements prevented 100% of bed bugs from reaching the sleeping surface. All six interior sides of the encasement are lined with a patented polyurethane membrane that bed bugs cannot eat or slither through, preventing bed bugs from entering the mattress or forcing them to remain inside and eventually die from lack of sustenance. A patented three-sided zipper with micro teeth prevent bed bugs from penetrating the closed zipper and the patented end clasp--where bed bugs typically pass--is sealed to ensure optimal protection. The mattress encasements are made from breathable, smooth polyester. Machine wash and dry. Queen and King fit 11" to 18"-deep mattresses; Twin and Full fit 7" to 12"-deep mattresses. Mattress encasements can also be used on a box spring.