{HEAD ~ Each pocket} is formed into {TAIL ~ a shape} forming a narrow opening portion at the inner race side and a wide opening portion at the outer race side 
is formed into
{ HEAD ~ Each pocket } is formed into { TAIL ~ a shape } forming a narrow opening portion at the inner race side and a wide opening portion at the outer race side
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL 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