This plate replaces the OEM PCV vacuum diaphragm housing on the valve cover to enable hooking up a catch can system cleanly. The plate is available with a 12AN male bung or 3/4" (19mm) hose barb machined integrally. New stainless socket head cap screws are included along with a 1/4" left hand drill bit to remove the OEM pentagon security screws. CNC machined in house from 6061 aluminum!