A fastener comprising a polymer composition [composition (C)] comprising at least one polyaryletherketone polymer [(PAEK) polymer], and at least one nitride (NI) of an element having an electronegativity (ε) of from 1.3 to 2.5, as listed in <>, CRC Press, 64th edition, pages B-65 to B-158, based on the total weight of the composition (C).