In {HEAD ~ the embodiment} shown, elastic coupling member 13 is formed as {TAIL ~ a spring member} 
In { HEAD ~ the embodiment } shown , elastic coupling member 13 is formed as { TAIL ~ a spring member }
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL