Cotton yarn thickness is expressed as count, written as S: 10s, 18S, 21s, 32S, 40s, and rarely 60 and 80. Higher count means finer yarn.
The British system still used in China: when one pound (454 g) of yarn measures 840 yards, the count is 1s. Ten times 840 yards per pound is 10s, and so on.
The mill note ties 21s, 32s and 40s to ordinary apparel and home-textile programs, with 60s and 80s described as rare.