The versatile TEC-S360 Isotope Fob is designed around the use of a glass tritium vial (not included), which will glow continuously for many years without need to charge it from sunlight or UV light. The TEC-S360 is very similar to the TEC-S323, but the viewing slots have been modified. The alternating slots have been rotated 90 degrees to increase the view of the tritium vial throughout a 360 degree rotation around the housing for a stunning visual effect. Hence, the model number "360". 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-S360 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-S360 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-S360 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