  In this work we study the classes of epsilon and nearly epsilon-strongly
graded rings by a group $G$. In particular, we extend Dade's theorem to the
realm of nearly epsilon-strongly graded rings. Moreover, we introduce the
category SIM$S-$gr of symmetrically graded modules and use it to present a new
characterization of strongly graded rings. A functorial approach is used to
obtain a characterization of epsilon-strongly graded rings. Finally, we
determine conditions for which an epsilon-strongly graded ring can be written
as a direct sum of strongly graded rings and a trivially graded ring.
