You've got to strategize, whether a single peak or the entire Pemi Loop is the day's itinerary. For staying cool and comfortable in warmer conditions, Marmot has you covered with the Syrocco, a woven, breathable trail shirt enhanced with moisture-wicking, quick-drying properties and UPF protection. As such, your skin breathes and stays dry even when it's humid, and you've got partial coverage once you're hiking above treeline.. . 100% Polyester AirExchange Plain Weave 2.5 oz./yd.. AirExchange Performance Fabric for Air Permeability. Packable, Breathable, and Lightweight. Ultraviolet Protection Factor (UPF) 25. Polyester for Quick-Drying and Wicking. Durable Flat-Felled Seams. Shirt Tail Hem and Single Patch Pocket. Weight: 4.6 oz.. Imported.