Our Quantum? MESF kits contain one blank population and a series of either four fluorescent microsphere populations labeled with varying amounts of Alexa Fluor^? 488, Alexa Fluor^? 647, APC, or R-PE, or five fluorescent microsphere populations labeled with varying amounts of FITC. The assignment of fluorescence intensity in Molecules of Soluble Fluorochrome (MESF) units is performed through direct comparison of fluorescence measurements from solutions of the pure fluorochrome with those from microspheres surface-labeled with the same fluorochrome. See PDS 849 to determine effective FP ratio. A free QuickCal^? analysis template is provided with each kit to aid in determining the expression level of cells, and for evaluating instrument linearity and detection threshold. Quantum? MESF kits are available in three sizes: A (20 tests), B (100 tests), and C (280 tests).