TOPTIE Yoga Racer Back Tank Top, Athletic Compression Tank, Junior JUNIOR SIZING - runs much smaller than US women's sizing. Please check our SIZE INFO in the description to get the perfect fit. If you are in women's sizing, please order 2 sizes up. 90% polyester / 10% spandex. Running singlet, sleeveless. Fitted design. Quick-dry fabric to wick sweat away and help keep you dry and comfortable.