Our Allergy Relief Bedding Is Designed Specifically To Prevent Dust Allergens From Becoming Airborne The Membrane-free Tight-weave Construction Prevents Dust Allergens And Pet Dander From Becoming Airborne No Membrane Means The Most Comfortable And Cool Night?s Sleep And Allergy Relief All Of Our Covers Are Laboratory Tested And Efficient Against Dust Allergens And Pet Dander Zippered Mattress Cover Twin 39 X75 X9 Six Gauge Vinyl Heavy Duty And Durable One Cover Per Package 100% Waterproof Fire Retardent Notice To California Consumers: Warning: This Product Contains Chemicals Known To The State Of California To Cause Cancer And Birth Defects Or Other Reproductive Harm