These ones. The ones with a wider lid are more like these - but they also are ~4ml or larger.
What an excellent gift! I'm sure he'll enjoy it.
If you want to get him some accessories I would recommend these containers: http://www.amazon.com/Soy-Sauce-Container--15-Bag/dp/B001AJ8HOG/ref=sr_1_21?ie=UTF8&qid=1354536165&sr=8-21&keywords=bento . It says their soy sauce containers but I mainly use them for salad dressing.
The silicone baking cups help keep things separate in the bento box until you're ready to mix them. Like so.
I know the square ones probably pack easier and are more reliable, but now I really want the little "Frequently bought together" fish and pig shaped bottles!
