"Low profile, lightweight, with balanced warmth"  01/09/13

The new Patagonia Capilene 4 material is thin, breathable and slightly stretchy with a grid pattern of heavier insulation (think R1 with 1/2 the pile). This is a material for layer lovers. Compared to the old Capilene 4, this trades off a moderate amount of insulation for a great level of breathability. In effect, it is less effective by itself, but makes a better base layer overall.When I have them on around town, I have never had to roll them up above my calves due to being too warm which I have had to do with other heavy-grade long underwear. I rarely notice my legs being too cold or hot... so far these are the best long underwear I have found.