The Cougartron Marking Head plays an important role in the marking process. It connects to the Lead Handle Cable (from a weld cleaner) with the special adaptor. In combination with the Marking Felt and Yellow fabric completes the marking head assembly used for direct contact with the metal surface. The Marking Head with Adaptor is included in both Cougartron Etching Sets. We recommend replacing the head if you see any signs of damage. Please note: This Marking Head with Adaptor is not compatible with our Marking Machines (MK12, MK612) . For that, you need to use the Marking Head without an adaptor WELC4029 Compatibility WELC4045 - Cougartron Basic Etching Set WELC4035 - Etching Set with Footswitch