The Columbia PFG Zero Rules Long-Sleeve Shirt feels super-soft against your skin, yet it's packed with technical performance. The lightweight 100% polyester shell is antimicrobial-treated to help reduce odors, ensuring that you stay fresher longer. Omni-Shade UPF 30 sun protection helps shield your skin against harsh UV rays. Columbia's revolutionary Omni-Freeze ZERO technology reacts with your sweat to lower the temperature of the material. The low-profile crew-neck collar fits snugly without being too tight. Modern Classic fit. Part of Columbia's PFG line, designed for maximum impact on the water. Imported.