What does an Einstein-De Sitter universe look like?

I know an Einstein-De Sitter universe is a "flat" universe, i.e. with a K ("bendiness", sorry, don't really know what to call it in English) factor of 0, but does that entail anything as to its contents? The Wikipedia page is quite lackluster on this aspect, and my astronomy course textbook merely slightly less so (it says it's made up mainly of "non-relativistic, dust-like matter").

And yes, it is flat (k=0) for the EdS model. Essentially it is the epoch at which only matter is thought to dominate (no contributions from radiative pressure or dark energy, $\Lambda$).