Known protective helmets used for motorcycle riding, flying and snowmobiling employ transparent visors that have heating elements to reduce and attempt to eliminate the build-up of ice, condensation and fog. A double-lensed face shield is provided with a pair of electrodes formed on an inner face lens, in the air pocket formed between the inner face lens and the outer weather lens. Substantially across one entire surface of the inner face lens is formed an electroconductive film. An upper electrode extends from a first end along an upper margin of the inner face lens on the film to a second end. On the opposite lower margin extends on the film a lower electrode from a first end to a second end. An insulated contact passes from one side of the inner lens to the other and connects the first end of the lower electrode with a conductor which extends on the opposite side of the inner lens towards the first end of the upper electrode. Power supplied across the first end of the upper electrode and the tail end of the conductor will result in electrical flow across the film inhibiting fog, ice and frost. Also provided is an assembly to permit the installation of face shields on helmets of different sizes and with openings of different configurations.