Half Moon Lumbar Cushion for Back Pain Relief, Leg and Knee Support and Sleeping with Removable Cover uses 100% high-quality memory foam that is hypoallergenic and provides excellent comfort and support to different areas of the body, such as the lower back, knees, hips, legs, or ankles, and is ideal for sleeping on your back, side, or stomach; for recovery after hip or knee replacement surgery or during pregnancy.