They have been particularly popular in French school canteens, which make it a childhood memory for many. I am sure that this nostalgic aspect helped with its r

They have been particularly popular in French school canteens, which make it a childhood memory for many. I am sure that this nostalgic aspect helped with its renewed popularity. One notable feature of Duralex glasses is that there is a number on the bottom that can go from 1 to 50. A tradition among schoolchildren is to look at that number, which is said to represent your age. In reality, it is the mold number, used for quality control, but that "age" thing is what most people remember it for.