Ultra-Breathable and Lightweight 4-Season Customer Favorite The Echo T-Shirt is built from ultralight bluesign®-approved recycled materials, perfect for everything from fall running and spring ski touring to summer hiking and winter base layers. The Echo is made from lightweight and breathable fabric infused with UPF 15 sun protection and ActiveFresh™ odor control technology, protecting from UV rays and perfect for extended trips into the backcountry. AirVent™ technology delivers superb airflow and moisture management during extra warm days on trail, and the flat-seam construction and reflective logo ensure next-to-skin comfort for layering and add visibility in low-light conditions. Truly an all-around essential and perennial OR customer favorite, the Echo T-Shirt is a do-it-all piece base layer for 4-season use in any environment