I've been searching all over and as of today May 17th, 2014, Autolite is the only company that makes Iridium plug for small gas engines. I bought this over a month ago to replace the Champion RDJ7Y in my 4 cycle 34cc Craftsman trimmer. I've used it twice since then. It runs alot smoother and quieter, or shall I say, not as loud, and the gas trigger feels lighter. This is the perfect companion to 3.4oz of full synthetic 10w30 motor oil and Shell 93 octane super unleaded gasoline in the trimmer. I let my grass grow to about 12" and with more power, it doesn't bog down as much. This plug model is quite standard and it also fits in my old 2 cycle Ryobi trimmer. Ditch those copper plugs. They cost more in the local stores than this high tech Iridium plug on AutoPartsWAY.I took the liberty of copying the cross reference numbers from Autolite's website for your convenient:Bosch 7814, HS7FChampion 5851, 851EZ, 855, 872, DJ6Y, DJ7Y, RDJ7YDenso T20MP-UE3 E3.16...