Part of why I went with the glass vial is becuase they have medical grade caps. Not teflon, but decent. Having spoken with a couple of lab techs I know, I concluded that whatever water vapor in there was all there was ever going to be in there, and the bottle itself is non conductive, so from a corrosion point of view, those hooks won't degrade in a hundred years. The glass also can't be pierced by the hooks, unlike the bag. And the little buggers are tough- I accidently stepped on one after knocking a bunch of the them on the floor, and they didn't break even though I had boots on and was on tile floor. And the trapped air provides enough bouancy to float, at least in tea (long story) so when someone foolish decides to use it as a bobber, so long as they make the loop right, it will work.

That, and I like the little vials.