In both of these embodiments preferably the retaining means includes {HEAD ~ a plurality} of {TAIL ~ projections} projecting axially around the perimeter of one or both of the ends of the cylindrical sleeve and the cylindrical insert includes a plurality of apertures equal in number to the projections located on the surface of one or both of the flanges and located in positions such that the projections fit into the apertures 
In both of these embodiments preferably the retaining means includes { HEAD ~ a plurality } of { TAIL ~ projections } projecting axially around the perimeter of one or both of the ends of the cylindrical sleeve and the cylindrical insert includes a plurality of apertures equal in number to the projections located on the surface of one or both of the flanges and located in positions such that the projections fit into the apertures
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH