I chose this as a base layer and mid layer. Around the house I wear it when the wood stove isn't cranked up and to bed to stay warm. It fits snug all the way around and has a zippered neck which I can crank down when I get warm.I primarily bought this as a back packing top but I think only on cooler days will I be wearing this. I am going to keep it for around camp and sleeping. My patagonia cap 2's are going to be my hiking top. I will use this in lieu of a capilene 3 or 4 top. With a fleece and shell over this I am quite warm. I hope this review helps you and I would buy this product again just to get it in a different color. I bought it in yellow and the dirt/pizza stains show. I am going to opt for a darker color if I am going to be wearing this on a thru hike of the AT.