What piece of clothing could you not do without?
I was out last night riding in mid 30Fs, and thought of how I missed my "Dickie" That neck warmer thing that looks like your wearing a turtle neck? I have two that are nice and long, so I can pull them up over my face if needed. It has been the one addition I don't think I could do without in the real cold. A close second are the arm warmers I made from old sweat pants. I found my arms get real cold when riding, and my core stays nice and toasty, so I made these liners for my windshirt I use for layers on my arms. I've done without them, but not often, when it gets really cold.
What are your's?