The surface portion is substantially circular when viewed in a direction of the axis and is non parallel to the axis and including {HEAD ~ at least two contact points} disposed at a lesser distance from {TAIL ~ the axis} than a region between the at least two contact points 
disposed from
The surface portion is substantially circular when viewed in a direction of the axis and is non parallel to the axis and including { HEAD ~ at least two contact points } disposed at a lesser distance from { TAIL ~ the axis } than a region between the at least two contact points
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH