Thermo Fisher Scientific has made improvements to the design of its Nunc 384-well polypropylene plates. To enable better sealing and re-sealing, the plates now have raised rims around each individual well. They are used primarily for storage and transport of chemicals, nucleic acids, and proteins. The plates are available sterile or non-sterile in four colors: natural, white, black, or blue. The black and white plates are used for fluorescence and luminescence assays, respectively, and the black plates help increase product stability by blocking light from photosensitive compounds.