DIN 6921, Non-Serrated Hex Flange Screw Frame Bolt
Non-Serrated Flange Screw (din-6921) Frame Bolts are hex washer head bolts with a flat washer bearing surface. They are made from high-alloy steel, and commonly used on truck frames, hence the name frame bolt. The flange eliminates the need for washers. They are covered under ASME Standard B18.2.1.