Referring to FIG. 7A, shown is a schematic drawing illustrating a top view of the needle and barrel assembly 300; FIG. 7B illustrates a left side view of the assembly 300 shown in FIG. 7A; FIG. 7C illustrates a right side view of the assembly 300 shown in FIG. 7A; FIG. 7D illustrates a cross-sectional view through the assembly 300 shown in FIG. 7A along line D-D; FIG. 7E illustrates a perspective