gauge of the insulation i the barrel ib will grip the insulation insufficiently firmly to afford the desired strain relief nevertheless if the shut height of the die 10 is too low in relation to the insulation gauge the crimped barrel ib will extrude the insulation i and the ends of the ears of that barrel may be driven against the core c thereby impairing its tensile strength if the shut height of the die 14 is too high in relation to the gauge of the core c the strands st of the core c will not be compressed into a voidless cold forged mass as shown in fig4 so that the connection cc will be of low tensile strength nevertheless if the shut height of the die 14 is too low in relation to the gauge of the core c the strands st may be broken off or unduly attenuated so that the connection cc is of low tensile strength in this case also the wire barrel wb is usually designed for crimping to cores c of a range of gauges for example a range of four gauges the associated insulation barrel ib being designed for crimping to insulation of a greater range of gauges for example sixteen different gauges since leads l having cores c of the same gauge may have insulation of a range of gauges for example a range of four gauges accordingly the shut heights of the dies 10 and 14 must be.