PerCP/Cy5.5 is a tandem conjugate. In our Lightning-Link PerCP/Cy5.5 the best result is obtained when the tandem is excited at 488nm, wavelength at which the PerCP has its maximum absorption. The excited PerCP functions as an energy donor, where the energy is transferred via FRET (Fluorescence Resonance Energy Transfer) to the Cy5.5. The Cy5.5 emits then the energy received from the PE in the form of long wavelength light at 700nm. Use in FLOW cytometry reported in scientific literature ( PMID 26483406). This kit can be used to label up to 100 ug of antibody, and is supplied in one vial.