Composed by more than 75% asbestos fiber and small than 25% cotton or other fiber, with color white. According to quality grade of asbestos fiber, it can be divided into: C grade, B grade, A grade, AA grade, AAA grade, and AAAA grade, different grade has different temperature resistance and tensile strength, the yarn can be reinforced by glass fiber yarn, brass yarn, and stainless steel yarn according to requirements.