ORIGINAL: Sport_Pilot
Presently platinum is about $1.720 per ounce and rhodium is $2,250 per ounce. So if OS is solid patinum instead of a platinum and rhodium, then it is the cheaper plug.
Yes that may be true, but Platinum is also almost twice as dense as Rhodium so for a certain volume or length of wire, then platinum is the more expensive material...
Regarding the plug length, I'm pretty sure that the OS#8 is a good match for the OS .10 FSR head, while other plugs would be too long.