  We revisit D3-branes at toric CY$_3$ singularities with orientifolds and
their description in terms of dimer models. We classify orientifold actions on
the dimer through smooth involutions of the torus. In particular, we describe
new orientifold projections related to maps on the dimer without fixed points,
leading to Klein bottles. These new orientifolds lead to novel $\mathcal{N}=1$
SCFT's that resemble, in many aspects, non-orientifolded theories. For
instance, we recover the presence of fractional branes and some of them trigger
a cascading RG-flow \`a la Klebanov-Strassler. The remaining involutions lead
to non-supersymmetric setups, thus exhausting the possible orientifolds on
dimers.
