The end on SAE flareless fitting nuts is usually a dark graphite coloration on account of lubricant coating. The fitting nut features a bonded dry film lubricant which aids while in the installation system to scale back torque and prevent galling. When the ferrule is in locale and set, the http://edwinswurp.blogminds.com/the-5-second-trick-for-sae-flareless-fittings-8965522