This product is W138 Cell Serum-Free Medium, a chemically defined medium specifically designed for the in vitro culture of human embryonic lung fibroblasts (W138). Its core formulation precisely matches the unique adhesion growth and metabolic requirements of this human diploid cell line. By optimizing key nutrients and cytokine combinations, it provides a stable and reliable in vitro culture environment for applications such as viral vaccine production and fundamental cell biology research. It also completely eliminates batch-to-batch variability, exogenous factor risks, and experimental interference associated with serum use.