A meditation cushion has one job: keep the hips higher than the knees so the spine can sit upright without muscular effort. Foam compresses over a session and stops doing that; buckwheat hull shifts to follow the shape of the sitter and holds its height, which is why it is the traditional fill.
The cover is cotton-linen and removes on a zip for washing, and there is a handle at the side. Because the fill is loose hull, the cushion should not be opened near small children. It weighs about 1.2 kg, so it stays where it is put.