In the heat of summer, it can feel like your feet will never be cool again. In Castelli's Free 6 Socks, though, you might start to feel a little better about the sweltering dog days of summer. Castelli used Meryl Skinlife, an ultra-light, ultra-breathable fabric, which also happens to be antimicrobial. That adds up to cool, comfortable feet that don't stink. Not bad for August.