Asker, the classification of "boxes" or "storage boxes" in the tenth edition of the "International Classification of Goods and Services for Trademark Registration" should be based on their materials and uses.

If it is made of metal, it is Category 6 “0613 Metal Containers”

If it is made of paper, it is Category 16 “1609 Paper and plastic packaging items not belonging to other categories” ”

If it is made of leather, it is Category 18 “1802 Leather, artificial leather products, boxes and travel bags, daily leather products not included in other categories”

Such as glass Materials or ordinary boxes are classified into Class 21 "Metal boxes for distributing tissues 210036, metal boxes for distributing tissues 210036"

Tips: The tenth edition of the "International Classification of Goods and Services for Trademark Registration" for general purposes Category 21 is sufficient.