Be cool. The trail's no place to be sweating through your clothes, so Marmot devised the innovative Aerobora shirt, an ultra-breathable, moisture-wicking, quick-drying combination enhanced with stretch construction and UPF protection. The result, built for movement and long days outdoors, lets your skin breathe and controls perspiration and, once you're at basecamp, compactly packs up, so it barely takes up any space.. . 100% Polyester AirExchange Plain Weave Stretch 3.4 oz./yd.. AirExchange Performance Fabric for Air Permeability. Packable, Breathable, and Lightweight. Ultraviolet Protection Factor (UPF) 25. Stretch for Increased Mobility. Polyester for Quick-Drying and Wicking. Durable Flat-Felled Seams. Shirt Tail Hem and Single Patch Pocket. Center Back Length: 30 in.. Weight: 6.5 oz. (184.3g). Imported.