From hot canyons to sun drenched cliffs, Marmot's Goat Peak Shirt will keep you cool and comfortable with the increased breathability of AirFlow technology. . Lightweight performance woven fabric of polyester plain weave. Engineered AirFlow technology increases breathability up to 50%, keeping you cool and comfortable. Mechanical stretch fabric for added comfort and mobility. Ultraviolet Protection Factor UPF 20. Durable flat felled seams with contrast interior stitch. Shirttail hem. Single patch pocket. Bluesign approved fabric a standard for environmentally responsible production.