Aside from the high cost, this is another perfect product from icebreaker. It's the lightest top you will find from the wool experts, perfect for warm-weather runs with a perforated wool back. While it may seem oxymoronic to run in wool when it's hot outside, there are two advantages to wool when the temperature rises. First, of course, is that wool sheds odors much better than synthetics. Even after drenching this thing in sweat, you can throw it in the sink, soak it with water, wring it out, let it air dry, and wear it again day after day with no odor build-up--my icebreaker gear smells better unwashed than a freshly laundered synthetic shirt after a few months worth of washes--making it ideal for those who plan to stay active while traveling without regular access to laundry, or those who prefer not to wash their gear every time they workout. Second, wool absorbs sweat and holds it close to your skin better than synthetics, which actually keeps you cooler when active in warm weather. It will chafe your nipples, though, so be sure to grease them up before you go.