from 200-500 days, these stars undergo significant changes in their observable properties. At some point in their lives, many if not most stars go through an unstable phase that leads to pulsation. They are evolving through the tip of the asymptotic giant branch (AGB) in the H-R diagram and are affected by two significant processes. In the interior, helium shell flashes cause large excursions in their luminosity’s and period on a timesscale of ten of thousands of years. In the outer layers, pulsation-enhanced