[en] A model of the first- and second-class hadron currents is proposed. Using the model obtained were the sum rules for spectral functions of vector and axial-vector second-class hadron currents. New mass relation checked experimentally is presented for the case of non-strange second-class hadron currents at sum rule saturation with corresponding physical states. The mass relation is also obtained for the case of strange second-class hadron currents. A number of relations was obtained for coupling constants of the physical states saturating the sum rules of the second-class hadron currents