SafeRest Premium LOW PROFILE UP TO 5.5" THICK Box Spring Encasement - Lab Tested Bed Bug Proof, Dust Mite Proof and Waterproof - Breathable, Noiseless and Vinyl Free - FITS UP TO 5.5" - Twin XL Independently lab tested and certified bed bug entry, escape and bite proof Surrounds the box spring on all 6 sides with a durable high-grade polyester surface material back coated with a water, bed bug and allergen proof membrane layer (great for those with asthma and allergies) Exclusive Micro-Zipper technology prevents all stages of bed bugs from passing through the zippers teeth 360 Secure zipper feature prevents accidental openings by sealing the end zipper traveler with a Velcro flap 10-year full replacement warranty and machine washable (registered with the FDA as a class 1 medical device)