For A Standard Twin Xl Size Mattress Measuring 39 Inches By 80 Inches, Use The Fit great: Fits twin xl size mattress perfectly with dimensions 39 inches by 80 inches; 11-14 inches deep pocket. High-quality zipper: To avoid the zipper getting stick or dislodged when changing the mattress encasement, we use the best zipper on this mattress protector. Also, the quality of stitches you can trust which will not popped and ripped for a long time. Waterproof and breathable: Not only the top surface is waterproof like other zippered encasement, the 4 sides and the bottom of this zipped mattress protector are waterproof, which can keep any liquid from leaking into your mattress. Super soft cotton terry: Stretchable knitted terry fabric fits the mattress easily and gives a comfortable feel while you sleep. We Can Provide: Our quality you can trust. And if you have any questions or size problem, please contact us. Our customer service staff will reply you within 24 hours.