This is a must have tool if you have a Honda 4 cylinder bike with the deep recessed spark plugs. You know this, because no other spark plug wrench or socket will fit in there! This one is pretty nice too, because it has a rubber ball at the top that holds the removable T handle part secure, so it doesn't slide out while your using it. + it holds the handle inside when you store the tool, so you don't lose it. Brilliant!
This wrench fits many of the Hondas with spark plugs such as the D7EA, D8EA and D9EA - used on models such as the CB350F, CB400F, CB500K, CB550 and CB750 from the 70's.
This fits spark plugs with 12mm thread and 18mm hex size.