The New Serta® Perfect Sleeper TWIRL Tight Top mattress has value added innovation focused on relieving aches and pains caused by pressure points. This model features Serta’s luxurious, breathable cover with a cool-to-the-touch sensation from technology that is plant-derived.* This biobased phase change material consists of 53% biobased content and is certified through the USDA Bio Preferred® Program.