The wood use to build this chair is machiche, an exotic wood from Central America. The mechanical properties of this wood allow this unique and ergonomic design.This chair is as sturdy and flexible. It can be used outdoor as well as indoor. The elements are linked between each other with metal. The chair conforms and does not rock on an irregular surface. Within up to 1/2" height difference, the four legs stay in full contact with the ground, patio or deck when a person is seated.