One point advise from Bento&Co
How to choose Bento Box

When you select Bento box, you should check its size whether it suits the amount user requires, its material, and its availability with microwave ovens and dishwashing machines.

Bento box with deep bottom or tall cover has unexpectedly large capacity. There is a Bento box type that two boxes can be folded as one after the meal.

Also some types are slim so that you can carry them in your business bug without difficulty.

And lately, there is such a Bento box of collapsible type.

In the cold season, items such as heat-retaining type, soup mug,

and rice ball box will broaden the joy of Bento.