The bags' exterior is an organic cotton canvas that has been dyed with an azo-free dye, and is then coated with a biodegradable, thermoplastic, aliphatic polyester that is derived from renewable resources, such as corn starch or sugarcane. The blue lining of the bag is made from recycled plastic water bottles and dyed using 100% organic vegetable dyes. Medium measures 15 inches by 12 inches by 1 inch when flat; large measures 16.5 inches by 14.5 inches by 1 inch when flat.