This invention is a fastener. The fastener has a body, a clamper and a restraint. The body is provided with a coupling part, which comprises a discontinuous raised rib going around an outer surface of the coupling part; the clamper is fitted over the coupling part; a recess going around an inner surface of the clamper; the raised rib is fitted to the recess; the restraint is arranged to surround the clamper, so the restraint is capable of restricting the clamper in a certain position range of the body.