Because you're at your best when natures does its worst. Fabric Weight: 4.5 oz. Fiber Content: 51% Polyester, 36% RedHEAT, 13% Spandex, Jersey Knit Brushed on both sides for comfort paired with MaeTRx RedHeat technology Hemmed ankles Wicking technology ColdPruf branding on chest, nape and thigh ColdPruf Athletic Fit - Close, moves with you fit.