The product is a mixture of 10 purified natural proteins with a range of 10~180 kDa, with a concentration of approximately 0.2~0.4 mg/ml per band. The 75 kDa band is a red pre-stained band, which is convenient for judging the accurate position of each band. The product is suitable for SDS-PAGE electrophoresis as a molecular weight reference for denatured protein samples, and can be used to monitor the separation of protein samples by electrophoresis in real time, and can also be used to detect the transfer efficiency of Western blot. Since the covalently bound dye affects the electrophoretic mobility of protein molecules, the product is suitable for roughly estimating the molecular weight of the target protein sample.