The tires are not very tight and usually move from their position when you get up. Also, because its construction is very elastic, for a person over 60 kilos, it will probably compress and become one with the back of the chair, so it will not be effective. Finally, in the center of the cushion, there is a hard plastic with protrusions (supposedly for massage), which if you don't wear thick clothing (jacket or sweater), it bothers or hurts you after a while

You can place it anywhere, it provides everything you need for your waist, it is ventilated through the holes so it doesn't heat up in the summer. I bought 2 pieces. We are very satisfied during working hours.