I buy my tritium gas vials from dealers China, I find them for 9 to 14 dollars.
Green is the brightest, tritium gas glows for up to 12 to 25 years depending on the purity of the trit. Tritium does not absorb light.
Left to right: brass lantern (glo fob) made by Harley Spalinger with 2 vials inside, TAD Gear copper Pharos Marker.. I removed the cheap glow powder/resin mix vial and replaced it with a real tritium gas vial, a titanium lantern with tritium imported from Switzerland, without any impurity sold by MacArmy with 3 windows..