Foam Pad Seat Cushion - 1pc Ergonomic Cover (Black) Easily attaches to most chairs and car seats with an elastic strap to wrap around Great for car seats, home or office chairs Great for placement on seats that are too hot or too cold Top Portion: 20" x 18.25" Bottom Portion: 17" x 18.25" 3/8" Foam Padding reduces back tension, aches and pains