100% Polyester ADDITIONAL CUSHION FOR LUMBAR SUPPORT - Slide or flip the back scoop upside down for adjustable lumbar support. Extra lumbar pillow can be used behind the back, under the legs, or under the arms for even greater customization. To hold the back rest in place, this item includes 2 removable / adjustable velcro tabs that attach in between the back rest and the back scoop. The exterior fabrics also have a natural friction that allow them to lock in place even without the velcro tabs. Head rest can attach to any part of the kind bed system by using the attached velco straps to affix to fabric on the side of any piece of the system. PROPER ALIGNMENT - Curved back wedge pillow follows natural curvature of spine for proper alignment and full upper body support. Slide the back scoop for adjustable lumbar support. To hold the back rest in place, this item includes 2 removable / adjustable velcro tabs that attach in between the back rest and the back scoop. The exterior fabrics also have a natural friction that allow them to lock in place even without the velcro tabs.