The surface has a subtle 5º slope that promotes proper pelvic posture, encouraging correct lumbar curvature. A depression in the center of the cushion eliminates contact pressure on the tailbone and soft tissue. The cushion is filled with a soft visco-elastic gel and supportive memory foam that disperse your weight to alleviate pressure points. The Seat Gel Foam Cushion features 34 cooling vents to help maintain firmness and the lightweight cushion provides superior comfort. Includes built in handle for portability. Gel and neoprene. 23"L x 16"W x 1 1/4"H.