Those tube "vaults" (found elsewhere on that web site) are simply PET preforms. They are later reheated and blown to shape to create 2-litre pop bottles for Coke/Pepsi. It seems strange how indestructible they are when small but so fragile when expanded!

I've got a few at home that I use for geocaching and to hold odds and sodds like magnets, screws, etc. I never really thought too much about them as far as storing liquids in them but really thats what they intended for!

A buck a tube is a bit expensive, you should be able to find them at about 1/2 that price if you look hard enough.

I bookmarked that site as they have some novel and useful items - only problem is that they don't ship to Canada because they use only UPS as their carrier. UPS |between| borders is the absolute worst way of sending any type of package.