These Billet Oil Caps are CNC Machined from 6061 T-6 Aluminum and are available in 4 different colors that include Red, Black or Blue anodizing. All caps are threaded to mount directly into a stock alternator stand or any of the JayCee Billet Oil Fill Models. 2 Breather Models with a choice of -8 or -10 AN and 1 non-breather. All caps come with an O-Ring for a leak-free seal.