A 5/8″ x 3-1/2″ Bolt & Nut Set is a heavy-duty industrial fastener with a 5/8-inch diameter and a 3-1/2-inch length, typically featuring coarse (UNC) or fine (UNF) threads. These hex head fasteners are commonly made from high-tensile steel (Grade 5 or 8) or stainless steel, and often come zinc-plated for corrosion resistance.