After 5 winters commuting I think I can say that there is no such thing as a single glove that is adequete for temperatures below 20, that includes my PI amphib lobsters. It is essential to layer on your hands & wrists. There is a lot of infiltration there. I try to overlap the cuff of my lining glove (silk, Outlast, or even Foxglove gardening gloves) over my base layer sleeves, then get my mid layer and jacket to overlap the lining glove and then the outer glove or mitt to overlap the jacket. That puts 5 or 6 layers over my wrists as opposed to the 1 or 2 layers on my legs and 2 or 3 layers on my body. If you keep your wrists warm the circulation to your fingers doesn't start to shut down nearly as soon. For outer gloves I use a pair of Thinsulate hunting gloves ( $5 at Walmart) down to 15-20F depending on the wind. I also use PI amphib lobsters from 25 down to 10. I like to be able to alternate so they have a chance to dry completely. Anything in the single digits I go with heavy wool mitts topped with leather mitts. The hard part of commuting in the winter is having the patience to spend almost as much time dressing as I do riding.