The author who previously reviewed a product called "KN Milk Carton Cap " that is useful for storing paper carton beverages on this site. I found a similar product in the 100-yen shop CAN DO, so I decided to compare it.
This product is named "Paper Carton Cap". It is made and used in almost the same way as the "KN Milk Carton Cap", but because the material is transparent, it has the advantage that the expiration date is not hidden even when attached to a paper carton.
Perhaps the airtightness is lower than that of the "KN Milk Carton Cap", and when I knocked it down when it was full, it leaked a little. However, if the leakage is at this level, it can be said that it is within the permissible range. And because it is easier to open and close because "low airtightness = loose tightening", it seems that children and elderly people with weak hands can easily use it.
The price of a "paper carton cap" is 108 yen (tax included). If you want to prevent the odor from being transferred to the beverage after opening it, or if you accidentally knock it down, why not give it a try?