Memory P.f. is a high quality memory foam that is designed to give the end user the “personal fit” of memory foam. Memory P.F. is the highest quality, low priced memory foam on the market and features a 6lb. density, the same as the market leader. Each piece contains pure visco elastic foam that is encased in a washable luxurious blue zippered velveteen cover. The N3001 Knee separator is a 10″ Long x 8″ Deep hourglass shaped cushion that provides ideal alignment for the spine, knees and hips. Also includes strap w/hook and loop closure that keeps the cushion attached to the leg while sleeping.