( 1) To ensure the spark plug can endure high temperature, pressure and vibration, we use corundum and porcelain for insulation. ( 2) The central electrode is made of copper surrounded by nickel so that it is great in conducting heat and electricity and less in building up carbon. ( 3) Using electrical heat to seal up the edges of the shell has made the inside completely air free .Meanwhile , we put the nickel coating on the outside to fight corrosion. gzyize@ gmail.com