D is a measurement unit of fiber thickness, also known as Dannier, referred to as D. For a fine bundle of silk, belonging to man-made fibers, refers to the 9000m long fibers in the public set the rate of return to the quality of grams, for example: 9000m long fiber weight of 70g, then the fiber that is 70D, the larger the value of the D yarn or fiber is thicker, and logically, the cloth will be thicker. Generally speaking, 100D is the thickest, 75D is the second thickest, and 30D is the thinnest.
S is the imperial number of count, it refers to the return rate in the metric system, weighing a pound of yarn, its length has a few 840 yards, known as a few counts of yarn. Generally, the yarn count of staple fiber is expressed in S. Staple fiber is expressed in English as Staple. The thicker the yarn, the smaller the S value; the finer the yarn, the larger the S value, such as 40S is finer than 20S.