Tritium’s half life is 12 Anna bit years, so your tube will be less shiny but there’s still plenty of beta particles flying about to last a bit longer.I bought a tiny plastic little glow-in-the-dark cylinder about an inch long, attaches to my key ring, useful for finding keys in the dark. Doesn't need charging up in light (it contains a wee bit of mildly radioactive gas which causes fluoresence of the pigments. Not gonna give anyone cancer!). The packet said it was guaranteed for 10 years....I bought it in 2010. Still works, best £10 I ever spent for worth.
Buy cheap buy twice.
Cheapo things of this nature tend to die an unnatural death and end up in the bin and have to be re bought.
Suck it up and get something decent and stop contributing to the planets demise.
/hippy
If anyone finds themselves touring on NCN 1 or Viking Trail and need a lbs I can highly recommend Lockes of Sandwich.