Fluid fillable, variable volume chamber.

The body has two welded foils (2) from plastic material, and is spaced one above the other. The foils form a hinge region along a folding axis (F). The foils are folded on top of each other along the hinge region by forming two partial portions of the body. A connection channel (4) is formed between the body portions, where the channel traverses along the hinge region. Each channel has a preset angle with the folding axis.