Hex bolt is the most widely used fastener with six-sided head. It can be tightened by spanner or socket wrench. Available in full thread and half thread versions. Common strength classes: 4.8,8.8,10.9,12.9. Material: carbon steel, alloy steel; finishes: blue-white zinc plated, color zinc plated, Dacromet, black oxide. Widely used in machinery, steel structures, construction and equipment assembly.