A sealed sphere of Fluorine/Nitrogen gas mix. Purity is approximately 30% F2 gas with the remainder being N2. Pure Fluorine is nearly impossible to store and display as an element sample since it will readily attack any glass containers it's stored in and destroy the sample. This mix is a much more stable alternative. The Fluorine will still slowly attack the inside of the sphere over time and it does show signs of clouding as can be seen in the photos.