Sadly while these are marketed as Ergonomic chairs, they are anything but ergonomic.  The seat is comfy, but there is zero back support (would be nice if their was a lower back adjuster) as the backrest is completely hollow (you can unzip it and see inside)  Made in China says alot too, that this is a production line item and not a high end quality item like the price suggests.  Very dissappointed!!