The fabric of slim sweater is fiber, regardless of animal fibers such as wool and rabbit hair. Because the raw material is curly, nylon should be added when spinning wool. Because of the good curl of nylon, the cohesion between fibers is large. After adding nylon, the strength of spun yarn is greatly improved.

In the past (more than ten years ago), the proportion of wool was above 95%, which was called pure wool. Now the proportion of wool is above 90%, which is called pure wool. Including cashmere products, nylon should also be added during spinning.