Solid colors consist entirely of cotton (100% Cotton). Heather Grey features a blend of 90% cotton and 10% polyester. Dark Heather and Heather Blue contain equal parts cotton and polyester (50% Cotton, 50% Polyester). Alternatively, Dark Heather, Heather Blue, and all other heather shades are made of 65% polyester and 35% cotton. For Girls' Heathers, the composition is 60% cotton and 40% polyester.