A fastener secures a trim cover to a foam pad. The fastener is positionable within a mold trench, which extends between a plurality of ends having stepped regions. The fastener includes a base having a mold surface and a foam surface opposite to the mold surface. The base extends between a plurality of base ends and longitudinal sides. The fastener also includes a plurality of trim cover attachment members extending outwardly from the mold surface for securing the trim cover thereto. In addition, the fastener includes a plurality of sealing flats that sealingly engage each of the stepped regions to prevent foam from flowing past the stepped regions and onto the plurality of trim cover attachment members on the mold surface.