The part between the connecting piece and the nut.Generally, a flat metal ring is used to protect the surface of the connected piece from nut abrasion and to disperse the pressure of the nut on the connected piece.Divided into flat washer – C level, large washers – A and C level, large washers – C level, small washer – A level, flat washer – A level, flat washer – chamfering – A grade, steel structure with high strength gasket, spherical washer, cone washer, beams with inclined washer, channels with oblique gaskets, standard spring washer, light spring washer, heavy spring washers, internal tooth lock washer, the serrated lock washer, tooth lock washer, external serrated lock washer, lock washer with only one ear, two ears check washer, lock washer with tongue, round nut with washer.