  Within the general frame of the upgrade of the collider DAFNE to the
neutron-antineutron energy threshold (2-2.5 GeV c.m.), modifications and
different options for the accelerator design are discussed and a possible
lattice for the Main Rings at 1 GeV is presented. The luminosity required by
the experiments for such a light quark factory is of the order of few 10^31
cm-2 s-1, easily achievable in the particle factory era.
