Jinghu Strings
Jinghu strings are chosen by mode before anything else. Xipi and erhuang are tuned differently, so the erhuang strings are made thicker than the xipi ones; swap one for the other and the tension lands wrong, taking the intonation and the tone with it. The outer string is the one that goes first, which is why players who accompany a whole evening keep singles as well as sets, and Beijing Xinghai is listed as separate xipi and erhuang inner and outer strings for exactly that. If you are not sure which pair your instrument is set up for, tell us the mode you play and what is on it now, on LINE at @linsculture.