  We develop the theory of ultracoproducts and weak containment for flows of
arbitrary topological groups. This provides a nice complement to corresponding
theories for p.m.p. actions and unitary representations of locally compact
groups. For the class of locally Roelcke precompact groups, the theory is
especially rich, allowing us to define for certain families of $G$-flows a
suitable compact space of weak types. When $G$ is locally compact, all
$G$-flows belong to one such family, yielding a single compact space describing
all weak types of $G$-flows.
