I now have a half -dozen of these thermal turtle neck tops from Cuddleduds - once winter sets they are my default top, as they keep me warm on winter walks, but look fine around the house, and let me keep my thermostat set lower than I would otherwise. I wash them in the washer, on a hand setting, and dry them in the dryer on low. I think they are true to size, except I am on the short side and the sleeves are a bit long on me, but I don't mind!
Very soft and flattering and doesn't add any extra bulk. Excellent shirt that has provided warmth with style. Bought it to wear under sweaters/tops/shirts and practically everything! Highly recommend. Only wish it came in x-small.