A dart point, the dart point having a distal end, a middle portion and a proximal end; wherein: the distal end is tapered to a point; the middle portion is substantially cylindrical; and the proximal end comprises a generally incompressible tapered retaining portion having a substantially continuous tapered retaining surface, being generally frusto-conical, wherein the taper becomes narrower in the direction passing from the distal end to the proximal end of the dart point.