Bed Bug Proof Box Spring Encasements Size: Twin Extra Long 3-sided BugLock Zipper system certified by an Entomology lab as bed bug entry & escape proof. Easy to Wash & Use: Wash in warm or hot water. Tumble dry on medium heat. 100 Percent Polyester Jersey-type fabric is stretchable & easy to take on/off box spring. For Box Springs Only: Do not use for as a mattress protector. Factory Warranty: 2 years for manufacturing defects