The front of this PathTag features data from the Periodic Table of Elements for Calcium, Carbon, and Helium: CaCHe. For geocachers though, this has a different association. The back is similarly themed with the chemical equation for Germanium Oxide: GeO. In this version of the PathTag, the formula on the front glows in the dark. When you purchase 5 or more of these tags the price drops by 25 cents.