This base layer is an essential part of anyone's outdoor layering system. In the fall, I wear it around town under a flannel or a down vest. When I'm on the mountain riding, I wear it under my puffy or fleece. Because it's made from wool, it doesn't get as stinky as the synthetic baselayers I have, and it's sooooo comfortable. I sometimes wear it to bed! It does a fantastic job with regulating my temperature, and when paired with my other layers, I am warm even on the coldest of Colorado days. Wool can have a reputation of being hard to care for, but I wash on cool and dry on low along with my regular clothes, and I haven't experienced any pilling or shrinkage. I loooooooove this baselayer!