Quote Originally Posted by gadfly56 View Post
Helium is super leaky stuff. I would be astonished if mass market devices of this type can keep a charge past a year or two. Unfortunately the next best gas is hydrogen, which is also pretty leaky and has additional issues, although not likely to be a problem at the quantity present in a light bulb. Neon comes in as a distant third for conductivity.
I suppose they might have a shelf life that starts ticking the moment they roll off the assembly line. It seems like helium can get through glass over time. The pressure is probably really damn close to atmospheric.