I’ve used this cushion for over four months, and it still has its thickness and cushioning properties. I don’t know that my back problems have anything to do with my coccyx or not, but I am somewhat more comfortable when I use this. I find it too deep (thick) for use in the car, unfortunately. (I use it with a desk chair and dining room chair.) The five stars is really because I’m impressed with the quality of the manufacturing and especially the foam. ..More