Yes the Yang Hao are all 100% wool with one small exception, the 3 Red Star 加料羊毫 brushes which have a small amount of Viverricula Indica hair added. This adds a slightly stiffer effect but is not equivalent to the wool/’wolf’ combination brushes which have (60–65%) weasel hair core, and 35–40% wool outer hair: these combination brushes are in a separate category 兼毫 Jian Hao Combination Brush so if you are looking under Yang Hao you shouldn’t be seeing these.