I was skeptical at first when I saw it online, but it went on sale, and how could you not try something with such great reviews? The first time I wore it I noticed the second skin type fit, which is ideal for base layers. I wore it inside, by itself, in a cold environment. It kept my temperature regulated at a comfortable degree, and also it made me feel surprisingly good about my body. Double plus. I've used it so much since then. It's never let me down. I wear it hiking, running, when I shovel snow, and even when I sleep on those cold nights. It's probably my favorite shirt in my wardrobe. I'll wear it by itself or as a base layer, and I love it both ways. I also got one for my mom, who is known for being cold on summer days. She feels the same way as I do, and she's way less active than I am. It's fairly light for a wool shirt, which is nice. It did shrink a little bit just from a wash, but it's not too bad. I'm 5'8" and have a longer torso, I usually go for a small, but grabbed a medium in this. After the shrink, it still covered me completely, I just need to stretch it out a little bit after each wash. No big deal, it's worth it.