Parkhurst & Oliff
Electrical self-purification ignition plug
 An electrical self-purification ignition plug comprising a porcelain insulator ignition leg provided at its end surface opposed to a grounded electrode with a conical depression, and a center electrode exposed to the base surface of said conical depression and made integral with said porcelain insulator. 
NGK Spark Plug Co., Ltd.
H H
H01T H01T
inventional inventional
Kanemitsu Shunichi Yasuhiko
Nishio Takagi Suzuki