What is this?

[pipskicks]

Saw a test tube, looked like gel inside, said it was the PG solution, and you're supposed to fill it up and when it gets low, refill it, the lady at the cigar shop knew almost nothing (and I'm a newbie) and she said it will last forever. To me it looked like it lasted until the gel dissapeared, but she said it just shrinks and then will expand when you add more. Anyone heard of this and is it good? She said it was a lot better than the normal humiidifier that comes inside the humidors.