A helmet includes a cap body which is provided with a chin cover portion defining the lower edge of a window opening formed on the front surface of the cap body and a shield plate on the cap body for closing the window opening. The helmet is formed so that a shell of the cap body is divided at a position...http://www.google.es/patents/US5212843?utm_source=gb-gplus-sharePatente US5212843 - Helmet
