HI
I HAVE BEEN runing glo engines40 to 1.80 size a total 26 years but over a period of 50 yearsi have never had a need to run any glo plug but a- K & B 1 L (is a medium heat range plug ) with or without an idle barthe plugs are the best medium long plug you can use for reliability and longevity ( and are a true long plugs) IMO-they last forever unless you have a very lean run OR you develope an air leak in your engine (that will take out ANY glo plug-)- the local hobby shop was were i got them until a few years ago -you can now buy them at : MERCO.com- i have been using the same glo plug since i was 16 years oldi am now 66 and fly RC for 20 years -now retired to central FLORIDA ( I HATE TO CHANGE WHAT HAS WORKED FOR ME FOR SO LONG ) the HANGER 9 glo plug seems to be more readily available and a very good glo plug i only fly two sroke glo engines so a very outstanding glo plug is a must to keep my fleet of 23 airplanes flying on a regular basis my glo engines run better than mostBEST REGARDS TONY