Product details:

If you want an extra wide cushion to fit an extra-wide seat, the Ultimate Purple Cushion is 4 inches wider and 2 inches longer to fit a wider variety of fannies and seats. The contoured groove at the back of the cushion will also help align your spine better and aid in adjusting your posture, so you can say to the world with a straight face, and a straight spine, that Purple really is "all that." The Ultimate Purple Cushions is the firmest and thickest cushion offered for extra support when the pressure starts to add up.