DIN 9021 refers to a specific standard within the German Institute for Standardization (Deutsches Institut für Normung) that outlines the specifications for large outside diameter washers, commonly used in mechanical and engineering applications. These washers are characterized by their larger outer diameter in relation to their inner diameter, providing a broader surface area against the material or part they are securing. This feature helps distribute the load more effectively, reducing pressure and preventing damage or indentation to the secured surfaces. The DIN 9021 standard ensures uniformity in dimensions, material composition, and performance characteristics, facilitating compatibility and reliability across applications involving bolted connections. By adhering to this standard, manufacturers and engineers can ensure that these components meet rigorous quality and safety requirements, thereby enhancing the durability and longevity of the overall assembly or structure.