Mr. Gasket baffled breather grommets are designed to virtually eliminate oil breather blow by, a common problem encountered on non-baffled valve covers with push-on breathers. No tools are required for installation, as the baffled grommets simply replace the stock grommets. They are made to fit most valve covers that use 1-1/4 O.D. x 1 I.D. grommets; these will not work with stud girdles, as they extend 1-1/4 inch into the valve covers. Packaged 2 per set.