In the preferred embodiment of the invention, the flat annular surface 34 at the tip distal end lies in a plane positioned at an angle of 15° to {HEAD ~ a plane} normal or perpendicular to {TAIL ~ the center axis} of the tip 
In the preferred embodiment of the invention , the flat annular surface 34 at the tip distal end lies in a plane positioned at an angle of 15 ° to { HEAD ~ a plane } normal or perpendicular to { TAIL ~ the center axis } of the tip
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 REL OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH