Seat cushions specifically designed for relief of coccyx and tail bone sensitivity usually include a cut-out or recessed area in the rear of the cushion.  These cushions are designed for seating comfort and extended sitting to help relieve pain from other chronic pain conditions, inflammatory pain, or to relieve pressure on the back and pelvic area during pregnancy.    The cutout at the rear of the cushion is near the base of the spine and is designed relieve pressure on the tailbone or spine.   Cushions come in different heaights, size of cut-outs and materials which affect the firmness of the cushion.