Shine Athletica Women's Workout Muscle Tanks - Powerful Fitness Flowy Scoop Muscle Shirt 65% polyester Preshrunk 65% polyester, 35% viscose for comfortable workout feel. Super light and relaxed flowy fit workout muslce tanks. This workout muscle Tee has over-sized arm openings for ease of lifting, running, fitness training, etc. Available in sizes XS-XL with 4 colors. FREE Returns S 0-2, M 2-4, L 6-10, XL 10-14, XXL 14-18