surface layer 14 acts as the principal working layer since it is adapted to act against the felt 21 in the nip n the surface layer 14 is constructed for example of relatively hard plastic material an appropriate rubber mixture or the like according to the invention passages or perforations are provided through the surface or outer layer 14 which are substantially similar to the perforations provided in a suction roll the passages 16 are spaced from each other by appropriate distances and open into and communicate with the cavities 15 if the cavities 15 have a spherical shape and the diameter of each spherical cavity is somewhat shorter than the radial thickness of the inner layer 13 at least one passage 16 opens into each cavity 15 on the other hand where the cavities 15 are constituted by elongated cylindrical spaces several passages 16 open into the same cavity 15 axially adjacent passages 16 are preferably spaced from each other a distance which is substantially equal to the spacing k between circumferentially adjacent passages 16 fig2 thus each passage 16 comprises a discrete conduit which passes through the outer layer 14 spaced by a distance k from axially and circumferentially adjacent passages and as seen in the drawings opens into a cavity 15 having a larger volume than the passage by virtue of the provision of the layered structure on the roll 10 in accordance with the invention the extension l 1 of the nip.