J.B. Expedition Adventure Travel Quick Dry Socks (2 Pairs) Content: 98% Polypropylene, 2% Spandex 2 Pack Dries In Less Than 8 Hours! Polypropylene- Provides the most effective insulation, highly breathable, and is an optimal temperature regulator PLEASE NOTE THAT WE ARE CHANGING THE CONSTRUCTION OF THESE SOCKS (05/06/14) BY ADDING MORE ELASTIC IN THE LEG SO THEY STAY UP BETTER! Ultra-Light Specific Weight- Non bulk construction promotes a better fit, invisible toe seams for added comfot, and provides protection against blisters by reducing friction