CF® dye bovine serum albumin (BSA) conjugates are bright and photostable fluorescent BSA conjugates for applications in which well-defined molecular weight fluid phase tracers are needed. These applications include studying the rate of endocytosis and exocytosis and following vesicle trafficking. CF® dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Far-red fluorescent CF®640R dye has excitation/emission at 642/662 nm.