For extending the length of threaded bar. Plated in Trivalent Chromium (Cr3) Zinc Standard metric thread" Thread Dia. mm: M8 Socket Size mm: 13 Height mm: 24.0 Thread Type: Metric Finish: Zinc & Clear Cr3 Material: Carbon Steel Timco Hex Connector Nuts - Zinc (Size M8 - 100 Pieces) in Silver