“Wave washers” are excellent washers that can be used for various purposes by forming a conical thin plate into a waveform shape. They serve to prevent interference between parts during operation and reduce noise caused by looseness. Additionally, as a means of preventing loosening during screw tightening, they are less likely to scratch the target object compared to spring washers. Wave washers, used in various locations, are often produced by spring manufacturers rather than washer manufacturers.