Twin (9 in Deep), AllergyCare 100% Cotton, Dust Mite Proof, Zippered Mattress Encasement 100% Cotton Made in USA or Imported 100% Cotton Encasing is effective against dust mites, pollen, pet danader, and other harmful allergens. Breathable, Cool, and Comfortable Allergen Barrier Allows Air to Pass through Ensuring a Great Nights Sleep. Six (6) Sided Zippered Mattress Cover Fully Encases the Mattress. Heavy Gauge Nylon Zippers with Coated Rustproof Metal Zipper Pulls. 4.59 Mean Pore Size (PMI Test Results)