Cushion is great, cover needs to improve
I agree with other comments: The cushion absolutely works, it provides great support.  I've had the simply seat cushion for two months, and the cover is already starting to separate at the seams, and the zipper pull fell off today.  The anti-skid bumps help compared to the old t-shirt I tossed over the cushion but not by much.
Rating: 4 stars