To obtain maximum support of the sacro-lumbar region, place the highest side under your knees. To improve blood circulation, place the lowest side under your knees. Duration of use varies according to individual needs. The composition is made of high resilience polyurethane foam (velva), designed to ensure stability of the cushion. With a comfort layer of high density, gel infused viscoelastic foam (memory foam) included. Easily carried or folded. Most Supportive for the knees/calves/heels. Measures 20Wx22Lx08H. 3 Layered bamboo viscose removable cover is antibacterial, hypoallergenic and breathes/absorbs humidity. Machine washable in cold water. Lay flat to dry. No ironing. No bleach. Additional covers are available.