  Motivated by the study of Weyl structures on conformal manifolds admitting
parallel weightless forms, we define the notion of conformal product of
conformal structures and study its basic properties. We obtain a classification
of Weyl manifolds carrying parallel forms, and we use it to investigate the
holonomy of the adapted Weyl connection on conformal products. As an
application we describe a new class of Einstein-Weyl manifolds of dimension 4.
