Coupling Nut, Material Grade/Class Grade 5, Material Steel, Finish Black Oxide, Thread Size 5/16 In.-18, Thread Style Fully Threaded, Hex Width 9/16 in, Overall Length 7/8 in, Dimensional Standards RoHS Compliant with Excemption 6, Material Quality Standards Grade 2, System of Measurement Inch, Thread Direction Right Hand, Color Black, Pack Size Small Pack, Rockwell Hardness 85-90 Rockwell on 15N Scale