40+ UPF Sun Protection Button-down collar increases sun protection and stays in place Full-length button front placket for easy adjustability Patch-on chest pockets with button-and-loop flap closures; left pen pocket Midback vertical vents for ease of movement and ventilation even when wearing a backpack Shirttail hem keeps your shirt in place during movement and stays put under a hip belt Patagonia Self-Guided UPF Hike Shirt Mens