The insert has {TAIL ~ 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 {HEAD ~ the polygon} 
The insert has { TAIL ~ 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 { HEAD ~ the polygon }
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL 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 HEAD HEAD HEAD HEAD HEAD HEAD