The tritium vials, needed to complete this lantern, are made up of a thin glass tube, sealed at both ends, with a phosphorescent coating on the inside of the glass and filled with tritium gas. The gas releases electrons, which energise the coating and that energy is then emitted as visible light. I'm not really sure what the output of the vials is in lumens. It will vary between colours, with green being the brightest option. Another issue is that since the vials get their energy from radioactive decay, the vial's output is constantly dropping as the tritium gas decays into hydrogen-3. Tritium has a half-life of 12.3 years, so after this time a tritium lantern will appear half as bright. I have never read about any quantified output figures for tritium vials, new or otherwise.