Spritech(TM Superior Comfort Winter Sanding Seat Cushion for Chair Car Seat Plane or Wheelchair Coffee 15.6" 15.6" This cushion is pure handmade, the size of the 2-3 cm error belongs to the normal range Superior comfort for a chair, car seat, plane or wheelchair Assists in the relief and treatment of lower back pain, numbness Patented design promotes healthy weight distribution, posture and spine alignment Reduces pressure on the?hip