Description of Target: QUANTUMTM FITC-5 MESF (PRE-MIXED) is comprised of five calibrated fluorescent populations in one tube, each with different levels of FITC fluorescence intensity, and one blank population of uniform microspheres that are approximately the size of human lymphocytes (7-9 um). The excitation and emission spectra of the microspheres match those of cell samples labeled with FITC.