These mittens are great. I've never been able to keep my hands dry and warm on those sub zero days but I have not had a problem yet! The liners help but even without wearing them, my hands are still really warm. I ordered a medium and they are just slightly small. I always have to put hand warmers in my gloves (no matter what, poor circulation) and I could use just a little more room in the wrist and thumbs. According to the size chart I fit on the lower end of the medium size so I would just say order a bit bigger if you need the room.