Harrisonwrote a review of The North Face Velocitee Crew Shirt - Short-Sleeve - Men's on September 18, 2009
Sweat keeps you cool because when water evaporates from a surface, it lowers the temperature of that surface. By drawing the sweat from your skin, these shirts increase the rate at which this process can happen, thereby making your natural heat regulation capabilities more effective. Thus, when you get a little warm, you sweat a little bit, the shirt amplifies the process and you cool down before you even know that you're sweating. When it's cool outside you stop sweating and then this shirt works like any other piece of clothing to keep you warm. In the words of Bill Nye, SCIENCE RULES.I especially love these shirts because they're low friction without being too slippery. Thus I can move around freely while rock climbing without feeling like I'm wearing a silk shirt from a 1980s disco.The only problem is that because this is a synthetic fiber, bacteria love it. Thus, you wear this while sweating and you instantly stink. The smell washes out easy enough, but if you like to get multiples wears out of a shirt before washing it, you should probably go with a wool-based or antimicrobial-treated shirt instead.
Sizing: I'm 6'1", 185 pounds and the medium is loose-fitting without being baggy.