Patagonia Men’s A/C Shirt. The ultimate performance shirt for hot and humid climates. A/C® Shirt fabric has an open-weave design and fast-wicking properties that keeps you sane in the August heat of the Deep South or the heavy humidity of the tropics. Like air conditioning for your skin, the A/C® Shirt has a breezy 100% organic cotton that allows maximum airflow. Its light fabric rests casually on your skin, and the clean short-sleeved shirt construction features only the necessities: button-through chest pocket and side vents at the straight hem.