Generally speaking, it won't break, even in the hottest summer. If I buy a lunch box, I think it is better to put things in stainless steel, which is not easy to break.

Nowadays, high school students seldom bring their own meals, but I think this habit is very good, which is nutritious and hygienic, and saves money and time. I don't know why there are few such habits in middle schools and primary schools in China.