NGK's unique V-Power design directs the spark to the edge of the electrode where it develops more rapidly, this increases ignitability even in lean burn conditions. In addition the NGK V-Power plug has all the features of their traditional plugs including corrugated ribs, pure alumina silicate ceramic insulator for greater strength and better heat transfer, copper core and triple interior seal. Technical Specifications - 14mm Thread, 11mm (7/16") Reach, 5/8" (16mm) Hex Size, Tapered Seat, Resistor, Solid Terminal, V-Power (V-Grooved Center Electrode), .060" (1.5mm) Gap