2 which consists of a highly elastic polyurethane foam configured with a non plane surface pattern of upright cone like bodies 4 other patterns may be used such as ribs extending in any chosen direction or a combination of cone like patterns and rib like patterns still other surfaces may be bulges having an oval or a rectangular shape or bulges having any other separately designed and chosen shape the underlying layer 2 may have a thickness t 2 which includes the height h of the cones 4 of e g 20 150 mm preferably 80 110 mm wherein the cones may have a height h of e g 15 50 mm preferably 20 25 mm and wherein the cones 4 may also have a mutual spacing s of e g 30 70 mm preferably 50 mm the cones 4 can be formed by a known technique by which a plane splitting of a foam block is carried out with the opposing outer sides compressed in a corresponding pattern in the embodiments shown only one side of the underlying layer 2 is construed with the truncated cones 4 alternatively it will be possible to have both sides of the underlying layer 2 construed with truncated cones 4 also the mutual spacings between the truncated cones 4 may vary so that the mutual spacings between the truncated cones 4 is different along one part of the underlying layer 2 as compared to other parts of the underlying layer 2 this may be especially advantageous.