How many socks do d represent

The number d represents the thickness of the stockings. The higher the d number, the thicker the stockings are, and the more durable they are. Otherwise, the smaller the d number, the thinner the stockings are, and the thinner the stockings are, the less durable they are.
D number and temperature:
3d-5d is an ultra-thin invisible silk stockings. It looks like it's not worn on the body, and the skin color of legs is even more mysterious with the slight change of the color of the stockings.
8d-15d is ultra-thin silk stockings, suitable for temperatures above 25 ℃.
20d-40d is thin silk stockings, suitable for the temperature of 18-25 ℃.
50d-80d is a kind of slightly penetrating meat stockings, suitable for 15-22 ℃.
100D-680D is impermeable silk socks, suitable for 10 ℃～ 20 ℃.
800d-2800d is medium thickness stockings, suitable for temperature of 8-15 ℃.
3000d-5000d is thickened socks and pants, suitable for the temperature of 5-12 degrees.
More than 5800d is extra thick cold proof socks and pants, suitable for the temperature of 3-10 degrees.
The cold tolerance of each person is different, because the temperature difference between the north and the south is different, the above data is only for reference.