For extending the length of threaded bar. Plated in Trivalent Chromium (Cr3) Zinc Standard metric thread" Thread Dia. mm: M16 Socket Size mm: 24 Height mm: 48.0 Thread Type: Metric Finish: Zinc & Clear Cr3 Material: Carbon Steel Timco Hex Connector Nuts - Zinc (Size M16 - 50 Pieces) in Silver