a protective device , such as a boxing helmet , rib or muscle protector , athletic mat , hockey helmet , motorcycle helmet and similar devices , is formed such that the major shock absorption is accomplished by a series of bowed , preferably plastic , members which flex when the device is subjected to an impact , so as to absorb the shock and dissipate its transmission to the user . because of the nature of these bowed members , when the shock has been dissipated , the member returns to its original position so as to be able to absorb further shocks .