  We study N=1 dualities in four dimensional supersymmetric gauge theories by D
6-branes wrapping around 3-cycles of Calabi-Yau threefolds in the type IIA
string theory. We consider the models involving $SU(N_{c1})\times SU(N_{c2})$
product gauge group without or with adjoint matter in terms of geometrical
realisation of the configuration of D 6-branes wrapped 3-cycles. We also find
simple geometric description for the triple product gauge group
$SU(N_{c1})\times SU(N_{c2})\times SU(N_{c3})$ interpreted recently by Brodie
and Hanany in the context of D brane configurations together with NS 5-branes.
Their introduction of semi-infinite D 4-branes appears naturally by looking at
the flavor group in the dual theory. We generalize to product of arbitrary
number of gauge groups.
