These socks use combed cotton yarn, which is a very soft version of regular cotton. Combed cotton doesn't have any impurities or short protruding threads, is stronger than regular cotton, and is made by treating the cotton fibers before they are spun into yarn.
This was my second purchase of CHUP socks. Those are the best quality socks you can ever own. My first purchase of their socks was from a shop in Japan, they have survived for wearing and washing for more than 8 years and still looking great. I love their vibrant color and cheerful patterns, they make the most boring outfit interesting!