Place the Symbia 2.5”on the surface where you want to sit. While seated on this posture cushion; the zipper placed on the right side provides a declination optimizing the natural curve of the lumbar region. 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 buttocks/hamstrings. Measures 18Wx16Lx2.5H. 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.