We're all just winging it. 

.: Made with 100% Airlume combed and ring-spun cotton, a lightweight fabric
.: Fabric blends: Ash and Heather Prism colors - 99% cotton, 1% polyester; Heather and Solid Blend colors - 52% cotton, 48% polyester; Athletic Heather and Black Heather - 90% cotton, 10% polyester.