ASICS Little Boys' Ventilation Muscle 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 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