I discovered Icebreaker while traveling in NZ and have rather quickly switching out my wardrobe for as much of the stuff as I can. This is a great shirt that can be worn as a t-shirt by itself as as an undershirt beneath a dress shirt or any other top. It is very soft (and my girlfriend loves it as a nightshirt) and comfortable. I use these shirts mostly for running and time at the gym, and they do a great job keeping you warm when running in the rain and wicking away the sweat while running when it is dry. These shirts are a bit pricey, but I feel well worth it -- I have bought a number of them and usually am wearing one most days. They are the best!

At this price I was a little hesitant, but I own a bunch of heavier weight merino stuff for skiing so I figured it was worth the risk. I wore it just the other day doing some bouldering in 95 degree heat and it kept me dry for a long time and finally when it did get wet(I was sweating like a mule) it magically kept me cool. I don't know how it works but merino is the best fabric on the planet!

Once you go Merino, you'll never go back! Lightweight, warm, cool, breathable, smooth as silk, and you don't need to wash it very often!