A method normalizes a feature of an object in an image. A high-quality semifinished fiber material can be provided in a simple and cost-effective manner by a fluid-permeable carrier material made of a thermoplastic being used as the carrier material. Since an elevation difference h1 is provided on both tip end faces so that the tip end face of the first air discharge mouth is higher than the tip end face of the first hose connection mouth, obstructing components about an air valve mounted on the first air discharge mouth are avoided. The retention system may be associated with the support structure.