The invention relates to fasteners comprising a flexible planar backing provided with a fastening element on its upper side and/or on its lower side, wherein the fastener consists of at least one generally Y-shaped one-piece section defined by two opposing arms, which are separated from each other by a recess, and by a third arm joined to the two opposing arms and extending away from said recess, wherein the shape and size of said third arm correspond to the shape and size of said recess.