The Beacon Pocket™ enables a fitted sheet to actually fit the mattress. We guarantee it. It is designed to go on easily, but it will not come off until you want to take it off; then, it comes off very easily. The design is novel and unique; therefore, Beacon Linens has applied for a patent. The design is simple, so it just simply works. It doesn’t matter what fabric is used, i.e., percale, sateen, flannel, microfiber, cotton, polyester, etc. Whatever fabric style, color, or pattern used in the body of the sheet, the same is used throughout the whole sheet. We don’t use sewn-in panels, velcro, straps, snaps, stretch fabrics, or other gimmicks. This sheet construction will work with any fabric. We simply add triangles into the corners that fit underneath the mattress corner. This ensures that the sheet stays put on the corners because that is where other sheets always come off. Our elastic is strong and pulls the sides, ends, and corners toward the center of the bottom of the mattress. This keeps the sheet smooth around the sides.