{HEAD ~ The insert} has a cross section forming a mount portion 50 with six straight locating sides 51 56 lying on the sides of an imaginary bisymmetrical polygon 58, and forming a radially outwardly extending arm 60, 62 at each corner of {TAIL ~ the polygon} 
{ HEAD ~ The insert } has a cross section forming a mount portion 50 with six straight locating sides 51 56 lying on the sides of an imaginary bisymmetrical polygon 58 , and forming a radially outwardly extending arm 60 , 62 at each corner of { TAIL ~ the polygon }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL