Various types of coatings are available - Xylan 1000 series, 1400 series, 142X series, Teflon, Ceramic, Mil-Spec Coatings, Halar, and Dry Film Lubricants.  The right coating selection is based on environmental considerations for the parts, such as presence of different degrees of moisture, heat, chemicals, etc.  These particular parts included B7 studs measuring 3/4-10 X 3-3/4 with accompanying 3/4-10 Grade 2H heavy hex nuts.