STAY-COOL WICKINGULTRA-BREATHABLEFLATLOCK SEAMS FOR COMFORTREFLECTIVE DETAILS 4-ounce 100% poly jersey body with stay-cool wicking technology 4.1-ounce 100% poly mesh back panel Self-fabric collar Reflective O heat transfer at back neck Reflective stacked O heat transfers at lower back panels OGIO Endurance heat transfer label for tag-free comfort Reflective O Endurance heat transfer at front left hem