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