ASICS Big Boys' Youth Ventilation Muscle Tank 100% Polyester Machine Wash Cool down poly, fabric designed to move moisture away from the skin as body temperatures rise Uv protection, good to excellent protection is provided through a 15-50 plus upf Flat lock stitch, this stitch keep from chaffing the skin and stretches with movement Reflective, reflective materials reflect light back to its source for enhanced visibility Stretch, fabric designed to stretch with movement and motion