Via Geekologie:

This is the $20 Mitten Flask. It's a pair of mittens with a 3-ounce (5-ounces too small) flexible flask hidden inside the palm of the left-hand mitten, with a bite-valve at the thumb. That sucks because 1. I'm left-handed and would prefer the flask be in the right mitten, which 2. they could have avoided by making the mittens ambidextrous, but 3. really should have just put a flask in both.