Sisu is a soft, durable utility yarn reinforced with nylon. This makes it ideal for socks, but because it is so soft it has become a favorite for utility wear, layered under snowsuits and jackets. It has also been a favorite for knitting kofte sweaters since the early 1980s, because the structure of the yarn brings out the pattern of these traditional knitted jackets. Garments knitted with Sisu have a long lifespan and can remain just as beautiful for several generations.