It's a clay pot inside a bigger clay pot, with wet sand in between the pots. As the water evaporates, it cools the inside of the pot where you can put vegetables, very useful in Africa where it gets really hot and there aren't electric fridges everywhere. We can definitely use this in the temperate regions too though, no reason why we shouldn't!
"To oppose something is to maintain it" -- Ursula LeGuin
Joined: Feb 17, 2012
Location: Arizona low desert
We use a similar approach here in Arizona. (We have no fridge) It works well in climates with low humidity because it works by evaporative cooling.
Instead of using pots, we wet down a shirt sleeve or pant leg and slip it over a two liter bottle to keep drinks cool in summer. I tend to just sit it in a couple inches of water so that it can wick it up through the day. If you have good airflow it works really nicely. Cool water to start with and a shady location will actually get drinks decently chilly.
You could easily cut the neck off a bottle so that fruits and veggies fit in, then put a moist cloth around it.