From the manufacturer's website:
The concave shape minimizes pressure. Made of soft, smooth material. Elastic headband holds patch securely.
Warning: This product contains natural rubber latex which may cause allergic reactions. If rash develops or pain persists or increases, discontinue use and consult a physician.
*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.