A flat speaker device capable of emitting loud reproduced sound with a relatively simple configuration is provided. According to one embodiment of the invention, only four fasteners extend through the associated apertures of the backing plate, the drum-in-hat adapter, the axle flange and the caliper bracket for securing the caliper bracket, drum-in-hat adapter and the backing plate to the axle flange. If the information provider does not sign on at the service provider within a specific time period by transmitting the ident code, preferably together with a handling instruction relating to the information item, the service provider deletes the information item.