What's it for?

See the chain hanging below the table?

Anybody know what is it for?

I was at Starbucks Coffee in Shenzhen on Tuesday and I found that under all the tables hang a chain... I wonder what it's for? Anybody know? One of my colleagues guessed that it's probably for the customers to hang their plastic shopping bags... I don't think so. But I really cannot think of any reason for having that chain! Do they have it in other countries too? It will be nice to find out.