Serta 3-Pound Memory Foam Twin 1 1/2-Inch Mattress Topper Memory foam responds the individual's body heat and weight to minimize pressure points and provide additional support Ideal for anyone looking to wake up more refreshed, no matter if they sleep on their side, stomach or back Designed to cradle and support the natural curve of the spine; relieves the daily stress that we place on our individual vertebrae Has three pounds per cubic foot (PCF) density; density is the measurement of performance and durability in memory foam and is expressed in pounds per cubic foot, not the actual weight of the product