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 a radially outwardly extending arm 60, 62 at {TAIL ~ each corner} of the polygon 
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 a radially outwardly extending arm 60 , 62 at { TAIL ~ 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH