The , the silk thread used in the instrument, is a pivotal part of its construction. This feature was not seen on the speculated nobility-style instruments because they used a more tension of theirs and valued the relict nature of their instruments. The commoners did all the innovations that made the not only a sturdy instrument, but more sonically adept. The was used in paper so the fine silk was in abundance in Japan. As of the beginning of the 19th century, an ivory called became the standard for the .