Advised by a gym teacher, this cushion is very helpful and responsive when we have a sitting job and lumbar problems, sacrum who move. Since it is of course air, one has a seating that moves and that is not destabilizing. On the contrary. It allows the pelvis to move in any small movements. It's a bit surprising at first, but oh so relaxing. By doing exercises at home it is even advisable to just go to a pool that is well reduced mobility throughout the day. There are explanations in the leaflet on the subject. I'm glad of that. It is fairly quiet and suitable cover is good.
