The insert has {HEAD ~ 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 {TAIL ~ a radially outwardly extending arm} 60, 62 at each corner of the polygon 
forming
The insert has { HEAD ~ 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 { TAIL ~ a radially outwardly extending arm } 60 , 62 at each corner of the polygon
OTH OTH OTH HEAD 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 REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH