In addition to its durable dual gel bladder that eliminates any gel migration, the cushion's unique cut-out design removes pressure from the coccyx bone and promotes healthy posture. Gel Infused Foam Wheelchair Seat Cushion w/ Coccyx Cutout -16" x 16" x3” If you work long hours sitting in front of a computer, spend many hours on the road, or are confined to a wheelchair, ProHeal’s gel coccyx seat cushion is a dream come true.