3.5cm Diameter Cords Hypoallergenic (they do not absorb water or sweat so they do not breed bacteria). Suitable for all types of hair (long and thick hair? Use 2 GummiBands for extra hold!). Gentle on hair, reducing breakage and styling damage. Reusable for years. When the cord stretches out, warm it up with hot air from a hair dryer or hot water to return it to it’s original shape.