Cool Compress: 88% Nylon 12% Spandex (body). Space Dye Stretch Jersey: 94% Polyester / 6% Spandex (insets). Built in stretch power mesh bra supports. Criss cross back with adjustable straps flatters and supports. Back key pocket with grip tape holds them securely. Space dye fabric insets accent. Reflective logo keeps you visible in low light.