In {HEAD ~ this extended portion} 11c is formed ribs 11h formed on both side edges and {TAIL ~ an extended piece 11d} 
In { HEAD ~ this extended portion } 11c is formed ribs 11h formed on both side edges and { TAIL ~ an extended piece 11d }
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL