The functional principle uses the self-tensioning of the round steel to connect the seat surface to the frame. Bent open by hand, the seat is ‘clamped’ into the recess provided for this purpose. The stool is of course also stackable and due to the dimensions and inclination of the legs it is possible to stack it almost infinitely. To replace the seat with a padded or textile-covered module, the frame is stretched so that the panel can be removed. The tension of the frame and the depth of the seat are calculated so that both elements form a safe unit.