Features: Glass tube, glowing, bright, visible in the dark. Long life span, requires full light to glow, and uses UV radiation very Suitable for decoration, jewelry, glasses, clocks and more. Suitable for indoor and outdoor use. Maintenance-free: easy to install, no maintenance required. Note: It glows immediately if you need to absorb light before use. If you need it to glow for a long time, you need to keep it under the light for an hour. The product is not a tritium gas tube. The price of a tritium gas tube is 10 times that of a glass tube. Dear customers, please pay attention to distinguish it and do not be deceived. Specification: Size: 1.5*6mm, 3*11mm