  We present new numerical hydrodynamical modelling of the evolution of
Asymptotic Giant Branch (AGB) mass loss fluctuations during the
post-AGB/Planetary Nebula phase. These models show that after ionization, the
observable effects of the mass loss fluctuations disappear in a few thousand
years, consistent with the fact that only few PNe have been found to be
surrounded by `rings'. We derive the observational characteristics of these
rings, and compare them to reported observations of the rings around NGC 6543,
finding a good match of emission properties and line shapes. We predict small
variations in the observable electron temperatures.
