VECTASHIELDHardSet™ Mounting Medium prevents rapid photobleaching of fluorescent proteins and dyes. After approximately 15 minutes at room temperature, the mounting medium will harden, the coverslip will become immobilized, and optimal antifade ability and refractive index of 1.46 will be achieved. Mounted slides should be stored at 4 degrees C, protected from light. VECTASHIELD HardSet Mounting Medium is compatible with a wide array of fluorochromes, enzymatic substrates, and fluorescent proteins. The refractive index is 1.45. DAPI is a counterstain that binds to nucleii and causes them to fluoresce with a blue color. This is useful for Fluorescence In Situ Hybridization (FISH) assays and other techniques where a general orientation to the location of cells and nucleii is helpful. An attractive alternative to VECTASHIELD HardSet with DAPI is VECTASHIELD Vibrance™ with DAPI (NC1601055).