PowerLayer Men's & Boy's Compression Base Layer Top Sleeveless Tank Thermal Under Shirt 80% Polyester 20% Elastane Lightweight and stretch athletic fit compresses key muscles to improve power and endurance Moisture wicking fabric is QuickDry keeping you dry, light and comfortable Mixed with technical performance fabrics which helps regulate your body temperature Flat lock seams eliminate skin irritation Perfect to wear beneath another top for gym, training or running