I had major spine surgery as a kid, they messed up, i was squirting CSF everywhere and i needed to go back down to surgery another 3 times before coming round fully....suffered ever since.I can't use computer seats anymore, not the ones i have anyway, i find myself kneeling on the floor a lot for relief in my hips and lower spine but doing this was messing my knees up, so when i saw this it looked ideal, the other types with the center pole are flimsy and restrictive.The first night i used this product i swear it made me high, i couldn't get out of it, MASSIVE RELIEF, this product is great from the design up, the materials are good, easy to assemle and sturdy construction, the rocking motion is great, the seats are firm and easy to reupholster, i can only think who ever designed this must have needed it, i use it everyday, REALLY HAPPY with it, a great buy at a great price :-)