The O Ring is a replacement part for the K4000 torch. You can identify where this part is used by cross reference to the parts manual below. The K4000 type gouging torch is a heavy-duty 1000amp carbon-arc gouging torch with a built-in 15o angled head and 360o 7ft swivel cable assembly. The torch is ideal for high-amp metal removal applications such as ship building and pressure-vessel manufacturing. It will accept a wide range of gauging carbons flat and rounded from 3.9mm to 15.7mm diameter.