Make contact with insulated wires without cutting or stripping insulation. Spring loaded double "V" clamp holds wire centered for piercing needle. Pierces insulation on wires from 22 to 14 AWG (0.030" through 0.180" diameter). Tiny hole left in insulation can be easily sealed. High visibility bright yellow body 6405 mates with standard .16" (4mm) banana plug test leads, with or without safety shroud. 6413 mates with standard .080" (2mm) standard pin tip test probe. Red or black color-coded cap for easy identification. Rotating banana jack will not twist test lead while the needle is screwed into wire.