The present subject matter provides a system for wireless communications between one or more wireless audio devices and other electronics for providing a rich set of streaming audio, control, programming and enhanced hearing functions. In particular, the present invention relates to a method for continuously producing a synthetic resin film having molecular orientation controlled in the MD direction. The surface of the magnetic material compact body is roughened, and then the external electrodes are formed via plating. When viewed in an axial direction, the outer circumferential surface of the main body has a polygonal cross-sectional shape within a range within which the protrusions are formed.