The picture below describes the components of thermos flask, which can maintain temperature
Hey, where is the overview. Just describe the main observations of this diagram in you overview for the reader to get an overall picture about what you are getting ready to report.
All in all, thermos flask with around 30 - 40cm total of length could control maximum temperature regulations.
Instead of doing this at the end as a conclusion, you better bring it up to be an overview. For this task, overview is more appropriate than a conclusion.