Vespa / Stella cooling shroud spark plug gasket

This is an insert gasket to plug the gap on your Vespa's or Stella's plastic (i don't know if it'll work with the vintage metal ones) cooling shroud, around the spark plug boot. Works with a NGK spark plug boot. The point is to keep air from leaking out around your spark plug boot in order to force as much air as possible down around the cooling fins of the jug and head. According to my CHT gauge, just by plugging this hole, I was able to drop the peak temp at WOT in 4th gear by a few degrees. T