With the Felpro cork gaskets I've noticed in the last few years that they've started installing small metal "rings" into the cork around each bolt hole. In theory, the metal rings are there to align the gasket and not distort the cork, but.... after the gasket has been in installed for a few hundred miles, the cork around the metal ring loosens and the metal ring will FALL OUT when you lift the valve cover off. Be VERY careful that none of these metal rings fall out into your exposed valve train.