BOLI MINI is our house gong dao bei ("fairness pitcher"—公道杯). Also known as a cha hai ("tea sea"—茶海), this half-pint pitcher is used in small format tea steeping (sometimes called gongfu or gongfucha—"tea with effort"). It makes a gongfu session "fair" by collecting steeps of equal extraction from a gaiwan or teapot to then be decanted into drinking cups; without it, tea poured into the first cup would theoretically be weaker than tea poured into the next (as the leaves continue to extract through the pouring process).
Certain small-format tea making methods, like Chaozhou gongfu, skip this step in favor of decanting into cups with a back-and-forth motion, ensuring each cup receives tea at all phases of extraction.
When serving groups of 2-4, a gong dao bei is necessary. For solo sessions, BOLI MINI holds steeps too large for a single cup. (Our house gaiwan is just under 200 ml; if the average tea cup is 50 ml, one steep is 3-4 cups' worth, making a fairness pitcher indispensable.)
Also functional as a yuzamashi ("hot water cooler"—湯冷まし) in Japanese tea steeping, and for directly steeping Chinese greens like anji baicha.
Blown by the same glasswares studio as Teapot BOLI, MINI features similarly high quality construction: