NGK VD05EMH Resistor Spark Plug Cap NGK resistor covers are manufactured using extremely durable phenolic resin and EPDM rubber Ceramic resistors are used to ensure optimum performance and reliability Resistor covers will withstand extreme heat, vibration, prevent flashover and are water proof 120 degree long elbow 5K ohm resistance nut terminal rubber sheathed compact type 10mm and 12mm thread