Polyester ADJUSTABLE & ELASTIC: Our sheet clamps adjustable range from 6.3 inches to 12 inches (16cm to 31cm), with an impressive maximum stretch length of 26.8 inches (68cm). The wide elastic bands are built to handle strong tension, keep your sheets in place and neat, fit to your crib, twin, full, queen, king, Cal king size mattress cover. Say goodbye to those annoyingly untidy or wrinkled sheets once and for all PREMIUM MATERIALS: Made with the finest quality polyester bungee band, durable plastic buckle, and robust metal clips, were strictly tested to make sure every sheet corner straps in a good working condition. PRACTICAL MATTRESS STRAPS: These versatile straps are a must-have for wrinkled sheet. They come in handy for securing flat or fitted bed sheets, as well as other covers, including hospital bed sheets, sofa cushions, mattresses, tablecloth covers, chair, boat, car, and motorcycle seat covers, ironing board covers, tablecloths, slipcovers, and more. Practicality at its finest SIMPLE OPERATION: Installing and removing our sheet holders is a breeze, taking only a few quick steps. The sturdy metal clips bite into the edges and corners of your sheets, ensuring a tight and secure grip that keeps them firmly in position. No more worries about pesky sheet sliding during your cleaning routine EXCEPTIONAL SERVICE: We offer outstanding service to you. Our premium bed sheet straps are backed by a 12-month money-back or exchange guarantee if any quality problem, and any emails from our dear customers will get friendly replied with quick response in order to offer you an excellent shopping experience.