The Simms TriComp Cool Long-Sleeve Shirt breaks the mold by using strategic paneling of varied materials to maximize comfort. All of the materials are rated to UPF 50 to protect your skin from the sun's harmful rays, but Simms maximizes flexibility at the back and airflow at the sides. Coolcore technology encourages heat to escape, while the synthetic fibers wick away perspiration and dry quickly to keep you comfortable.