  Recently N. Seiberg has shown that certain N=1 supersymmetric Yang -- Mills
theories have the property that their infrared physics can be equivalently
described by {\it two different} gauge theories, with the strong coupling
region of one corresponding to the weak coupling region of the other. This
duality leads to interesting results about the infrared dynamics of these
theories. We generalize Seiberg's ideas to a new class of models for which a
similar duality allows one to obtain rather detailed dynamical information
about the long distance physics.
