As outlined above, the He opacity bump at around \({\log\, T}~\simeq~4.7\) is responsible for a convective zone which occurs close to the stellar surface and is very inefficient: only a very small fraction of the heat flux is transported by bulk motions in this region. The upper boundary is typically found at an optical depth in the range \(2 \leq \tau \leq 10\), where \(\tau\) is the Rosseland mean optical depth. Below this convective zone, the Fe opacity bump at around \({\log\, T}~\simeq~5.3\) is associated with a more efficient and extended convective region.