3 in one masu, urushi finish
A masu was originally a square wooden box used to measure rice in Japan during the feudal period. Masu existed in many sizes, typically covering the range from one to (ittomasu, c. 18L) to five go (gogo masu, c. 0.9L). One masu was supposedly enough rice to feed a person for one day.
Today masu are largely used for drinking sake, as the advent of modern rice cookers and a higher calorie diet in Japan has made them impractical for measuring portions of rice, and the standard size is one go, or 0.18039L.