Our donut-design seat cushion filled in 3.94in-thickness space slow-rebound memory foam, with middle hollow design and front and back curved slots, is great for provide ergonomic support for your buttocks and thighs while ensure excellent breathability and reduce body weight pressure. The cushion with size of 17.32x15.35in(LxW) is suitable for most chairs, like office chair, armchair, couches, wheelchair, car seat, etc.. It\'s a perfect gift for those have long sitting time and driving time and who suffer from sciatica, herniated.