This product is prepared by labeling high quality F (ab') 2 fragment of goat anti-mouse IgG (H+L) with CF®640R dye. 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.