"This aspect applies throughout the needle including the part of the barrel where the fluid first meets the constriction at the opening of the barrel (i.e. entry-aperture) which will preferably be an entry-aperture of smaller inner dimension than the bore of the barrel, i.e. the end is not square and the included angle is below 90???, in the range 3???-60???, e.g. 45???." . . . .