Double-sided tooth gasket: when assembled, the inner oblique tooth surface is relative, and the outer radial relief surface is in an occlusion state with the contact surface at both ends. When the connection is vibrated and the bolt becomes loose, only the two inner oblique tooth surfaces of the washer are allowed to be staggered, resulting in uplifting tension, so as to achieve 100% locking effect.Mainly applies to precision optical instrument, machinery, automobile and other high-end products.