Large FIRM Wellness Seat Cushion (Size: 18" x 14" x 1-3/4" to 3-1/2". Direct from the manufacturer and ONLY available at Amazon) Large Size: 18" x 14" x 1-3/4" to 3-1/2", Color: Black Made of furniture-graded, firm foam cushion for use in the home, car, or office Fits most bucket seats Features zippered, machine-washable cover with built-in carry handle Cutout section suspends the tailbone, providing relief for the coccyx/tailbone area