5 8 11 x 10 Carriage Bolt 316 (A4) Stainless Steel USS Flat Washers Zinc Plated The heavy duty flat head features The heavy duty flat head features under head cutting nibs and a T40 6 lobe drive that eliminates cam out and drives flush without pre drilling These American made washers are engineered from thru hardened medium carbon steel to provide exceptional strength and prevent loosening in high stress environments 5 8 11 x 10 Carriage Bolt 316 (A4) Stainless Steel is made from A4 316 Stainless Steel providing superior corrosion resistance and durability to ensure a long lasting product for outdoor and marine applications With a tensile strength of 80ksi this bolt will provide a secure and strong hold for your application