A hearing aid includes a housing and a battery drawer at an end of the housing which is pivotable relative to the housing and includes a protruding portion which, when abutted against a surface, will cause the battery drawer to pivot to an open position so that electric power to the amplifier in the housing is disconnected. The dendrimers can be used, for example, in the treatment of arthritis. In the AC mode, the input terminal is coupled to an RMS circuit through a capacitor. Items are placed in the hopper and, via gravity, fall to the bottom of the hopper where they contact the periphery of the rotating disc. The storage flap may be folded away for storage under the rear seat cushion when not in use.