Monoclonal mouse anti-fluorescein reacts with the fluorescein moiety of FITC and FAM. This product is prepared by labeling high quality monoclonal mouse anti-fluorescein IgG with the far-red fluorescent dye CF660R. CF660R absorbs at 663 nm but can still be sufficiently excited by the 633 or 635 nm laser with emission at 682 nm in the borderline spectral region between far-red and near-IR fluorescence. CF660R is significantly brighter than the spectrally similar Alexa Fluor? 660. More importantly, CF660R is extremely photostable, making the dye ideal for confocal microscopy.