This is a -6 ORB (-6 AN with O-ring) port plug. It's aluminum and anodized black.
FRAGOLA 481406-BL BLACK ALUMINUM 6 ORB PORT PLUG #6 6AN -6
FRAGOLA 481310-BL BLACK ALUMINUM #10 ORB HEX SOCKET ORB PORT PLUG
BTR 12AN-ORB Port Plug - Black -12 o-ring Fitting for Brian Tooley Valve Covers
Redhorse Low profile -08 ORB port plug - black
-6AN ORB Hex Head Block Off Port Plug with O-Ring, Black Aluminum AN6 AN Fitting
-10AN ORB Hex Head Block Off Port Plug with O-Ring, Black Aluminum AN 10 Fitting
