The main thing I like about this is the subtle and the little notch at the back, as it does an EXCELLENT job at relieving the pressure and pain from my tail bone. I also like that this stays secure and doesn't wiggle around like the donuts do.It also lets me sit a little higher up, so "standard" chairs are more appropriate for my height. The pillow is also super comfortable. It feels just like my memory foam pillows...thats because it is made with memory foam. Consequently, this forms to my body so I get the support I need while being comfortable. The cover is also very breathable, so you won't get oddly warm sitting on it, like you may with other pillows after a while. Overall, I am very happy with this! It satisfies what I need and want for a seat cushion.
Want to check this out for yourself? Here is the Amazon product link:
http://www.amztk.com/cool-cushion
*I received this product for free in exchange for my honest and unbiased review*