A method of fabricating an extended drain MOS transistor which reduces a design rule and prevents the generation of leakage current. , provided the articles have similar diameters for a given holster. The gap seal protrusion part is integrally formed adjacently to an underlip of the underseal, and is in contact with a terminal end face of the side lip of the side seal without a gap. In one embodiment, the central passageway extends through the irrigated finned ablation head, defining an opening at the distal extremity, with the slots extending from the base to the opening.