The insert has a cross section forming {TAIL ~ a mount portion} 50 with {HEAD ~ 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 the polygon 
The insert has a cross section forming { TAIL ~ a mount portion } 50 with { HEAD ~ 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 the polygon
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD 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