This leg pillow (leg spacer) Support is made with a higher quality, More supportive memory foam than most-Knee pillows help in reducing lower back stress when you are sleeping: Temperature-sensitive memory foam interacts with body heat to gently mold to your shape and provides customized comfort. The between the knee pillow helps align the spine while you are sleeping and prevents your back from twisting. Knee Pillows-Relieve stress, Strain and stiffness in lower back and legs.