This is a handy little item. Basically, it's a bolt-in breather opening for a valve cover that can be used to install a breather cap, an oil fill cap, or a breather with a PCV valve.
To install this item, you must make a 1-7/16" hole in the valve cover. You may want to purchase 91011033, our billet breather and/or 91011034, our billet PCV valve.