The versatile TEC-S323 Isotope Fob is designed around the use of a glass tritium vial (not included), which will glow continuously for many years without the need to charge it from sunlight or UV light. Seven slots on each side of the housing allow for maximum tritium visibility, while still offering superior protection for the glass vial. Smaller than our standard Embrite glow fobs, the Isotope fob allows you to mount a tritium vial directly into the metal housing without requiring the DIY kit. You can also change out the vial anytime you like for different glow colors. Complete your EDC collection with the functional and stylish TEC-S323 Isotope Fob, which provides just the right amount of light for locating items in the dark. Perfect for attaching it to your keychain, camping gear, zipper pulls on gear bags or jackets, or try it on the pull chain on your ceiling fan. Where will you clip yours? TEC-S323 Isotope Fob Features: Custom designed to hold a standard 3mm x23mm tritium vial (sometimes specified as 3mm x 22.5mm) Bead blasted, uniform matte finish Available in your choice of stainless steel finish or our exclusive Black Diamond Finish (see "Specifications" tab for details) Smaller size than our standard glow fobs What you get: (1) TEC-S323 Isotope Fob (3) Rubber plugs for tritium vial containment (1 required plus 2 spares) (1) 11.1 mm [7/16"] diameter split ring for attachment to other items Important Note: Product DOES NOT include tritium vial