  We explore the properties of five-dimensional supersymmetric gauge theories
living on $5$-brane webs in orientifold $5$-plane backgrounds. This allows
constructing quiver gauge theories with alternating $USp(2N)$ and $SO(N)$ gauge
groups with fundamental matter, and thus leads to the existence of new $5d$
fixed point theories. The web description can be further used to study
non-perturbative phenomena such as enhancement of symmetry and duality. We
further suggest that one can use these systems to engineer $5d$ $SO$ group with
spinor matter. We present evidence for this claim.
