The stopper has {TAIL ~ a first end portion} and {HEAD ~ a second end portion}, the first end portion being fixed to the cover 
The stopper has { TAIL ~ a first end portion } and { HEAD ~ a second end portion } , the first end portion being fixed to the cover
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH