Thanks for the tip! I found them at our local grocery too. They're called "King Soopers" here in Colorado, but they are part_of/owned_by/whatever Krogers.

They were on sale for $5.39 this week (normally $5.99) for that 24-pack. If we have any more Spring blizzards this year, I'll go out and try one in the blasting wind and blowing snow. I'll probably dip it in a bowl of water before the test too - be as hard on the thing as possible to see if it's suitable for real-world survival conditions.