A pneumatic device for varying a contour of a seat bearing surface includes a carrier foil TF composed of a first and a second foil ply which are arranged adjacent to one another. The pneumatic device has a first bladder for varying the contour of the seat bearing surface, including a bladder chamber which can be filled with pressure medium (DM). The pneumatic device furthermore has a first pressure medium line connected to the first bladder and which is formed by connection of the first and second foil plies along a line-side connection seam to create a pressure medium connection to the bladder chamber of the first bladder. One foil ply has, in the region of the first bladder, an opening in order to form a pressure medium channel to a further bladder, which can be filled with pressure medium and is connected to one of the foil plies.
