The extended piece 11d is {HEAD ~ arc} shaped at {TAIL ~ the free end portion}, which protrudes from the free end portion of the second joint portion 2c of the core 2 
shaped at
The extended piece 11d is { HEAD ~ arc } shaped at { TAIL ~ the free end portion } , which protrudes from the free end portion of the second joint portion 2c of the core 2
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH