E3.66 is a 14mm, 1.000” reach plug with a taper seat. It fits a wide variety of late model applications, especially Hemi applications. E3 automotive plugs have three legs securing the DiamondFIRE electrode to the shell. This allows for excellent heat transfer and helps to create more turbulence in the cylinder. The patented DiamondFIRE side wire is proven to increase power, reduce fuel consumption and improve hydrocarbon emissions in long-term use. The unique ground electrode and full-size center electrode also provides optimal performance for a guaranteed five years or 100,000 miles.