A fastening for use on a garment comprises a base, and at least two flat spikes initially projecting from the base for being pierced through the garment into apertures of a hasp, and then for being deflected into a clenched condition against the hasp, there being at least two cold-pressed grooves each opening into an outer surface of the fastening and extending longitudinally thereof across a shoulder or joint between the base and a respective one of the spikes. The fastening accordingly has a greater hardness in a region around the grooves than at other regions thereof so that the fastening is resistant to bending or other deformation around the grooves when the spikes are pierced and clenched.
