Our locking corner pocket stays tight - at any angle. Raise the foot, raise the head, do the pillow tilt...no problem. QuickZip corners are engineered to keep on keepin' on. Sewn for a custom fit, vertical elastic stretches up and pulls down to stay snug. We reinvented the fitted sheet with a two-piece design that is quick to change, easy to fold, and won't pop off. Each Fitted Sheet includes a base and a zip sheet. Extra 'add-on' zip sheets are sold separately in a variety of colors & fabrics