Carbon Fiber 1K refers to carbon fiber yarn containing 1,000 individual carbon fiber filaments (fiber bundles). The "K" in "1K" here stands for "thousand", which means 1,000 fiber filaments. 1K yarn is thinner than common thick yarns such as 3K and 6K, and is used in the manufacture of high-performance composite materials, such as aerospace, automobile racing, sports equipment, electronic products and other fields.