Its shape is like a round ring. Before tightening the nut and bolt, it is fitted on a stud or bolt. It is used to secure the tightness of a joint, screw, etc. and it becomes easy to open the nut-bolts and their threads are protected. This washer is in the shape of a ring cut by spring steel. Its ends are slightly raised up and down due to spring tension. These washers are placed above or below the nut or bolt and tighten so much that both their ends face each other and become leveled. These washers are used to prevent a nut from loosening. These are used where there is vibration, or jolts occur. This puts pressure against the nut, preventing the latter (the nut) from turning and working loose. Even if the fit is a bit larger than the diameter of the bolt, with the washers help nut bolt can be tightened easily.