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.
Designed to remove broken exhaust manifold studs on 4.6L, 5.4L 2 valve, 5.4L 3 valve and 6.8L v10 Ford engines without damaging the block.
Interchangeable plates ensure drill is centered on the broken stud. Depth gauge for drilling is marked on the template. The stripped screw extractor is then used to remove the broken stud.