E3 Small Engine Spark Plug - 13/16-Inch Hex Socket Replacement spark plug Fits most small engines Replaces Champion models N9YC, N11YC, N12YC. RN9YC, RN11YC, RN12YC; Replaces models NGK B6EB11, BP5EA, BP5ES, BP5ES11, BP5EV, BP5EY, BP6ES, BP6EV, BP6EY, BPR5ES, BPR5ES11, BPR5EV, BPR5EY, BPR6ES, BPR6EV, BPR6EY, BPR7EY11, BPR6EBL11, BU8ET, BUR6EA11, BUR6EB11, GR4, GR45; Replaces Autolite models 63, 64, 65, 66, 405, 646, 4263, 4265, AP63, AP64, AP66, AP646, APP64, APP646, XP63, XP64, XP646, XST4265 Designed to increase horsepower and lower emissions: quicker starts save on fuel and increase fuel efficiency up to 13% 14 mm thread diameter; .75" reach; 13/16" hex socket