Was it meant to isolate the bottles so the drink remains chill for an extended period? Never saw something like that.

Until I saw the picture, I had so thoroughly forgotten about these that your title conjured no mental image.

I remember these mostly as soft drinks served at expensive restaurants as a way to keep the refill inclined riffraff out.

I think I also remember seeing them as mixers for bartenders at catered events, but I’m not a hundred percent sure on that one.

They’re probably still around, definitely won’t have biodegraded