When sourcing carbon fiber yarn, the most critical factor is the Tow Size (K-count), which represents the number of filaments per strand (e.g., 1K, 3K, 12K). For high-performance applications, you must evaluate the Tensile Strength (MPa) and Tensile Modulus (GPa) to ensure the material can withstand specific mechanical loads. Additionally, verify the Sizing Type, as the chemical coating on the yarn must be compatible with your intended resin system (e.g., Epoxy, Polyester, or Vinyl Ester) to ensure proper bonding and structural integrity.