Self-locking hexagon nut (locknut) with Unified National Coarse (UNC) thread, an American screw thread with coarse pitch. Fitted with a nylon ring to prevent loosening due to vibration etc. Thread diameter-5/8 Inch Coils per inch-11 Thread type-UNC Wrench/Spanner size-15/16 Inch Height-19.4 mm Material-Steel Surface treatment-Zinc-plated Quality-8.8 DIN standard-985