I had mittens like this when I was a kid, with the cord that threads through the sleeves. I remember taking the mittens off and having them hang from the end of my sleeves. It is such a good idea that I wonder why they stopped making mittens like this. It must be a mitten maker conspiracy!
Handemade from 100% wool yarn in soft pink and blue stripes. This pair is available at Ogekko for $13