This circular part is called "ishimochi," and the montsuki that has such an ishimochi is called "ishimochi no montsuki"; in the Edo period, a cheap montsuki had no ishimochi on its cloth, but today such ishimochi-free montsuki are rarely seen.
この円のことを石持ちと呼び、江戸期の安価な紋付の場合、紋を入れずにそのまま仕立てることもあった（このような紋付を石持ちの紋付と呼ぶ）が、現在ではめったに用いられない。