Polyester [RELIEVE PRESSURE POINTS] - Do you wake up with back and joint pain because your mattress is too firm? Then opt for this memory foam mattress topper. It is an ideal choice as it can soften your mattress, adapt to your body shape, and relieve pressure points, providing contouring support [STAY COOL THROUGHOUT THE NIGHT] - The twin memory foam mattress topper from Sweetnight is infused with cooling gel to absorb and dissipate the heat. Separately, its cover features the breathable mesh fabric backing to promote airflow for a more comfortable, less sweaty sleep [Sleep With Peace Of Mind] - The foam materials used in our twin memory foam mattress toppers are CertiPUR-US certified, ensuring that you are sleeping on a safe and reliable mattress topper [DOUBLE ANTI-SLIP & NOT EASY TO MOVE] - No more worrying about your topper slipping off the mattress during the night when you toss and turn. The non-slip mesh fabric backing on the bottom of this topper enhances friction with the mattress. Additionally, it comes with adjustable elastic straps to securely hold the topper in place on the mattress DIMENSIONS OF YOUR MATTRESS TOPPER: Twin: 39" x 75" Twin XL: 39" x 80" Full: 54" x 75" Queen: 60" x 80" King: 76" x 80" Cal King: 72" x 84" TIPS YOUR MAY NEED: - Please allow 48-72 hours for your mattress topper to air out and regain to its shape in a ventilated area. A slight smell is normal and will fade away in a few hours. Please don’t worry. -Different mattress toppers feature different firmness. Let your sleeping preferences and needs guide you. It may take you some days to break in a new mattress topper. Please give it a try. -If your mattress is heavily sagging or damaged, it may be best to replace it. A twin memory foam mattress topper is not for replacing a heavily damaged mattress.