Filament count is the number of individual filaments that are included in each tow. Tow is the thread that you see in woven fabric or spools of carbon fiber. Each tow is made up of thousands of individual filaments; the “k” represents 1000. For instance, a 3k carbon tow is made up of 3,000 individual carbon filaments. The higher the filament count, the thicker the material. Thicker material is harder to form around bends and compound curves, and the increased bending or “crimp” from thicker tows can reduce strength. Filament count choice should be determined by the engineering requirements.