I ride when it's cold....I like to be warm. So...I see this on a few vendors' websites A* Tech Race thermal top Basically, it's the thermal Under Armor but the front of the torso, and the front of the arms down to the elbow have a windbreaking material sewn in. At 80mph into a headwind wearing my perforated jacket in low 60 degree temps I actually felt no sign of wind coming through my jacket. Obviously it was.....so that silly shirt seems to actually work. When it got to 70 this morning I was actually warm at highway speeds. Sitting in the shade it off the bike it definitely feels warmer than without....so I guess that's the whole "thermal" thing... Ummm so yeah...if you ride where it's cold.....it's something you might consider.