A coil structure of open ventilated type stereoscopic wound-core dry-type transformer, comprising wire disks formed by wound wires and fixing parts. A line is wrapped around the frame rest and the frame member of the bicycle. A stretchable or flexible electronic device is supported by the substrate inner andor outer surface, depending on the application of interest. The audio output from each of the host computers may be mixed or switched for output to the speakers as desired. Finally, additional filler cement is provided under pressure to the inside of the tubular implant.