Features: Tritium gas tube, self luminous, bright and visible in the dark. Long life span, glows continuously for 15 - 25 years. Perfect for decoration, jewelry, glasses, clock, etc. Suitable for indoor and outdoor use. Maintenance free: easy to install, no maintenance required. Size:1.5*6mm/2*12mm Notice: Color may be slightly different from the image due to different monitor and light effect Packing: 1x Tritium Gas Light