Each pair supports the National Parks Conservation Association (NPCA) to celebrate, protect, and preserve our nation’s most inspirational places for present and future generations. • Small fits women’s US shoe sizes 5-9, men's US shoe sizes 4-8, and EU shoe sizes 36-40. • Medium fits women’s US shoe sizes 9.5-14, men's US shoe sizes 8.5-13, and EU shoe sizes 41-47. • Sustainable • Certified Organic • Certified Fairtrade • Certified Vegan • Members of 1% for the Planet