When making 10 pieces of nigiri-zushi from 180ml of rice, the size is considerably large, categorized as 'oo-nigiri' (a big-size nigiri-zushi), which size was popular from the Edo to the early Meiji period.
ちなみに1合で10個の握りずしならかなり大きな握りでいわゆる「大握り」、江戸-明治初期を思わせる大きさである。