https://www.superiorwasher.com/washers/9212/Belleville-Spring-Steel.html
This video clip talks about a specific type of washer known for its reliable deflection or added shock absorption. Belleville spring steel washers are a fastening assembly that comes with the natural and flexible strength of spring steel which allow the washers to deflect. These are the stackable type of washers with enhanced shock-absorbing properties as they are stacked one over another.
Belleville spring steel washers are used in various industrial applications where flexible strength and durability are required.