The Astroman Sun Shirt is our best-selling lightweight, stretchy, and durable fabric, featuring a UPF 50 sun protection rating. Named after the legendary route in Yosemite Valley, the Astroman was built for exposed and rugged climbs, hiking, paddling, and backpacking. For any activity where staying cool and collected is the top priority, the Astroman Sun Shirt is a must-have.