form fitting and warm
It was about 8-12 degrees Celsius here in Montreal yesterday and I wore this base layer under my 'race winter long sleeved jersey' and they both kept me very warm and comfortable. so warm in fact that I had to undo my jersey! when I first opened the base layer I didn't think it was going to fit, but it's very form fitting and snug without feeling constricting. I'm about 5'11" and 70kg and the medium fits perfect.