STAY-COOL WICKINGULTRA-BREATHABLEFLATLOCK SEAMS FOR COMFORTREFLECTIVE DETAILS4-ounce 100% poly jersey with stay-cool wicking technology (White and Pace Yellow are 4.6-ounce) Self-fabric collar Reflective O heat transfer at back neck Reflective stacked O heat transfers at back Heat transfer label for tag-free comfort Modified set-in sleeves