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