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