https://www.jnzcsb.com/products/flange-nuts.html china hexagon flange nut, which have a wide flange at one end, act as an integral gasket, which distributes the pressure of the nut across the part being secured, reducing the possibility of component damage. The flanges can be serrated to provide locking. The serrations help prevent the vibration of the nut from moving the fastener, enhancing retention.All Rights Reserved