The NGK Sparkplug is a high quality NGK spark plug designed using the latest technology to give optimum performance over the Lawnmowers entire rev. range. The electrode tip is made of special nickel alloy ensuring superior heat resistance, durability & incorporates an insulator made of state of the art high alumina ceramics that offers sure sparking. The central electrode with copper deeply inserted in the tip quickly dissipates large amounts of heat, preventing overheating & fouling. With its solid construction this will ensure superb gas-tightness and the Special powders to connect the insulator and the metal shell offer strong construction too! Through extensive research & development NGK has developed a range of spark plugs specifically aimed at the horticultural market. The Thread diameter is M14, Thread reach is 9.5mm and Hex size 19mm. They fit various manufacturers including Husqvarna, Makita, Stihl, Brushcutters & chainsaws.