  The alternative $SU(4) \otimes SU(2)_L \otimes SU(2)_R$ gauge model, which
allows unification of the quarks and leptons at the TeV scale, is studied in
detail. We discuss the implications for nucleon decay, B and K rare meson
decays and neutrino masses. We also explain how this model solves the gauge
hierarchy problem without using supersymmetry or extra large dimensions.
