This cushion is so comfortable. It reduces back pain from sitting for long periods of time. I did try this on a flat surface after I did my video and it did get a bit uncomfortable to sit on after a while, but works great on other seats. It is about 17.7 x 13.7 x 2.8 inches in diameter and weighs about 1.3 pounds, so this is easy to carry around. It is very soft and the memory foam is not made from a cheap memory foam. You can even take the Navy Blue cover off of it and wash it when needed by using the zipper opening on the back of it.
I have a lot of lower back pain when I sit in some seats for awhile like my kitchen chairs when my family and I play board games. I usually have to sit on a pillow because I start to hurt from sitting in the chair. This made me feel like I had great support. I love it. The price is pretty okay as well.
If you would like to purchase this item it is on Amazon for $25.95 at this link; http://www.amztk.com/coccyx-cushion
If you would like to see my full video review it is on my YouTube page; https://youtu.be/i83gGBYmPXI
Disclaimer: I received the product from the seller at a discount in exchange for my honest and unbiased review of this product. I do believe that giving the most honest and reliable review may help other customers like me meet their expectations and helps sellers improve their designs to meet the needs of their customers.