Holds up to Six Tritium Vials: Individual bores retain up to six 3mm x 11mm glass tritium vials (NOT INCLUDED), which are visible from both sides of the housing. This offers maximum visibility of the tritium glow regardless of which side is facing up. Customize Colors to Suit your Style: Combine different colored tritium vials for a beautiful effect. The tritium vials (NOT INCLUDED) are easy to install, and the design provides a simple way to remove the vials if you want to exchange them for different colors. Durable Protection: The Grade 5 titanium housing is lightweight, yet extremely rugged to protect your glass tritium vials. Unique Design: With its 2-sided visability, this coin style titanium fob can be carried on a keychain, attached to zippers, mounted as a necklace, or you can even remove the jump ring and simply carry it as a unique pocket coin. The TEC-T311-6X Isotope Atom is a unique and eye-catching accessory that combines functionality with a touch of scientific flair. The TEC Isotope Atom is a coin style titanium fob designed to hold numerous glass tritium vials (not included), which will glow continuously for many years without the need to charge it from sunlight or UV light. Locate your bags in that pitch-black hotel room, find your keys in the dark, or simply have the most unique glowing necklace charm. Whether you use the Isotope Atom as a functional zipper pull or to simply identify your gear, there are a multitude of uses that will look absolutely amazing.