This all stainless steel washer is used on flywheels to prevent gouging of the surface under the bolt head. It absorbs and evenly distributes the pressure from the bolt to the flywheel face to improve torque and prevent loosening. Often the bolt can gouge into the face of the flywheel which can lead to loosening during riding and a loss of torque, this leads to the flywheel slipping on the crankshaft which can cause key way and bore damage. These are included with all Jetinetics flywheels and are offered as a spare part or upgrade to existing installations. Sold individually (photo shows 2 washers).