Unlike flat washers, wave washers (AKA wave spring or spring washer) are purposefully uneven (non-flat) washers that flex to absorb vibration. In machine and motor applications, the “wave” lends a compensating spring force that allows for dimension variations. When preloaded ahead of bearings and shafts, they apply a load on the face of the bearing that can help to reduce noise and vibration by establishing contact between the ball bearings and the collars. Items vary by the bolt sizes they fit, thickness, package quantity, and outside and inside diameters, among other considerations. For more on washers, see our retaining ring washers, lock washers, and sealing and cushioning washers.