The Ortho Wedge Seat Cushion is a foam seat cushion designed to alleviate pressure on the tail bone (coccyx). This wedge-shaped cushion has a cutout for the tail bone. The wedge shape tilts the pelvis forward for proper seated positioning. Made of resilient polyurethane foam, the cushion has a breathable, machine-washable velour cover. DIMENSIONS: 12.25 x 16.25 inches.