i use these for spring skiing, hiking when cold or fishing.  they are lightweight.  when it's super cold, i use these under my fleece long johns.  i don't know why it's so hard for find good thick fleece long johns, but when you combine the two long johns, you can withstand extreme cold.  wicks moisture away no problem.  i have worked super hard in these and never noticed any moisture.  if i wear these with ski pants and no fleece long johns, you can feel air and if it's really cold, it doesn't do enough.  great base layer but don't expect them to do the job alone when you get below 20 degrees F.