VALVE COVER OIL FILLER CAP -TWIST ONThis chromed breather/oil filler cap fits in any 1 1/4" valve cover hole. 2 1/2" dia. X 2 1/8"New & improved, this plug features a chrome-plated top w/embossed Mr. Gasket logo in the center. Fits all GM-OEM or aftermarket valve covers with 1.22" dia. hole.