Bosch spark plug ???


Has anyone used the Bosch F06CS0 spark plug in a flathead ? Got a used engine and it had it in it, it has copper spacers on it so it doesn't go to deep into the chamber, Just wondering if it is a special plug, never seen one before.
these aren't the thin index washers that we all use, theses are about 1/8" thick each, stacked on top of each other, creating a total of 1/4". I realize it was done because the plug is a 3/4" deep, just wondering if anyone has seen this
The guy must have really liked that plug to go to that trouble or he did it to save $$ because he had a bunch of 'em just laying around.
That plug shows up as a NASCAR racing plug. Looks like it's a cold plug similar to the AutoLite 3910X. I didn't look up the specs.
List at $25 each so he ain't doing it to save $$.
Nothing wrong with doing it.
Maybe the only way he could get the heat range plug he wanted.
It's kinda like a surface discharge plug, flat surface w/ one little electrode pointing in towards the center , Nice thing is no indexing needed !!! This was in a Checkered Flags engine, not sure if they put it in or someone else