This "D" refers to the fineness unit of sock fiber, which is called how many grams per 9000 meters.

Take Mrs. Langsha's stockings as an example:

At present, the thinnest one is 5D, and 10D and 15D are all ultra-thin stockings, which are suitable for ladies to wear in summer.

50D, 80D, 120D and 150D have moderate thickness, which is suitable for ladies to wear in spring and autumn.

300D to 2000D are extra-thick warm stockings, suitable for ladies to wear in winter. Generally, they are made of velvet (the stockings made of core-spun silk are thinner).

1600D velvet stockings are basically close to ordinary cotton trousers (called "autumn trousers" in the north).

Friend, I hope my answer will satisfy you _