The DIN 6921 standard specifies the requirements for hexagon flange bolts with a reduced shank. These bolts are commonly used in various industries for applications where a smooth surface and a high-strength connection are needed. The flange design helps distribute the load over a larger area, reducing the risk of damage to the connected materials. DIN 6921 bolts are available in different sizes and materials to suit different requirements, making them a versatile choice for many engineering projects.