US Patent 8166573 Helmet system with interchangeable outer shells

A helmet system comprises a base shell, a set of outer shells, said each outer shell selectively and adjustably geared for placement on and over the base shell in an interchangeable mode and position thereon as desired by the wearer, a connector detachably engaging said each outer shell to the base shell, and a first guide rail slot that includes an upwardly extending portion that the outer shell lies on and in, so that the upwardly extending portion extends between the base and the outer shell to form a buffer there between.