Applicable to all textile floor coverings with a thickness not greater than 20 mm. The tetrapod comprises a metal casting with four legs each of which has a polyurethane foot at the end. The top of each foot is hemispherical. The measurements of the hardness of the tetrapod food top is described in Annex A. The multi-drum system, as illustrated in Annex B, may be used, provided that it meets all the requirements of this Technical Report.