Valpolini are from what I've seen a plain metal based gasket with what looks like a pressure sensitive sealant coating. I've used them on rocker covers and they are very good and far superior to the composite gaskets of any kind, silicon or otherwise. The Guzzi timing cover gasket is a similar style but a true "crimped metal" gasket with pressure sensitive sealant so the metal base has been formed to provide some spring to it which means it doesn't rely entirely on the sealant. The "spring" mean