Beaver Professional Keratin System Hair Building Fibres 12g or 28g with Optional Beaver Fibre Hold Spray The beaver hair fibres are a cosmetic breakthrough that immediately gives men and women thicker looking hair and transforms your appearance in just a few moments Made from pure organic protein, beaver hair building fibres are completely undetectable, resistant to wind, rain and perspiration, yet easily wash out with shampoo. Restore your confidence and roll back the years with this incredible innovation in hair care. How Do Beaver Hair Building Fibres Work? Beaver hair fibres are made from natural organic keratin protein, the same protein that hair is made of.