Polyester quick-dry, wicking and temperature regulating performance flannel with engineered yarns to trap air for insulation and warmth Flannel is double brushed for comfort and warmth Ultraviolet Protection Factor (UPF) 50 protection from UV rays Double needle flat-felled seams for durability Articulated sleeves for freedom of movement The Phelps Midweight Stretch Flannel Shirt is a highly-technical men’s stretch performance flannel with quick-dry and moisture-wicking construction that traps air and enhances warmth. With engineered stretch, articulated and gusseted sleeves and sun protection, this flannel is well-suited for an active lifestyle.