Seat base foam gets flatter with age. Our pillows are thick and juicy, and fit our seat cover kit perfectly. For shorter drivers, these seat bases are particularly wonderful because they put you just a bit higher, especially if your old foam has seen a lot of miles and has thinned with age. Also, thick seat base foam makes your drive more comfortable. This seat pillow is an important barrier between your butt and the road, and a nice thick one just feels so much better. Sold individually.