Abstract: A new self-mating mechanical fastener is disclosed, which comprises a base sheet and a multiplicity of parallel, narrowly spaced, elastically deformable ribs projecting from the base sheet. The ribs comprise a stem portion attached to and substantially upright from the base sheet and at least one flange attached to each side of the stem portion and spaced from the base sheet. At least the outer portions of the flanges desirably project toward the base sheet. The cross-sectional profile formed by the ribs is substantially uniform over the length of the ribs, but in the direction transverse to the ribs has a regularly repeated deviation from the profile that would be formed by a full population of equally spaced, identical, undivided, symmetric ribs.