Flat washers can relieve pressure, increase friction, seal, shock absorption, and secure. Spring washers can increase the friction between nuts and bolts, prevent bolt loosening, and improve the stability of the connection.

Car gasket is a component used to connect structures, usually a flat metal ring, placed between the connected part and the nut. It can effectively protect the surface of the connected structure from scratches from the nut, while dispersing the burden of the nut on the connected structure. There are various types of washers, each with different sizes, thicknesses, and materials, so their functions also vary.