Of course, everyone knows that laser-sealed borosilicate glass vials that are internally coated with phosphor will create a cold energy that produces a light source when injected with gaseous tritium. It's as plain as the nose on your face.
The manufacturers of our Glowrings, who produce military equipment and other need-to-see-at-night items, have taken this everyday nugget of basic science and made it their business.
A Glowring is small enough and tough enough to attach to anything you might need to use in the dark, a bunch of keys being the most obvious. But because they can glow for up to a decade, you can leave them hanging off things that only come out once in a while like fishing gear and camping equipment. It does have to be pretty dark to see the glow, but that's the point.