The 6405 is a set of black and red insulated Piercing clips with banana jacks for connections to 4mm Test leads. The Piercing clips allows users to make contact with insulated wires without cutting or stripping the insulation of the wire. Clips can pierce insulation on wires from 22 to 14 AWG (0.030" (0.76mm) through 0.180" (0.46mm) in diameter). the tiny hole left in the insulation can easily be sealed.